UNIVERSnTgrCftLIFORNIA 

COLLEGE  of  MINING 
DEPARTMENTAL 
LIBRARY 


•   *  • 

BEQUEST  OF 


SAMUELBENEDICTCHRISTY 

PROFESSOR  OF 

MINING  AND   METALLURGY 

1885-1914 


THE 


EVOLUTION  OF  MINE-SURVEYING 
INSTRUMENTS. 


BY 


DUNBAR  D.  SCOTT  AND  OTHERS. 

tl 


COMPRISING  THE  ORIGINAL  PAPER  OF  MR.  SCOTT  ON  THE  SUBJECT, 
TOGETHER  WITH  THE  DISCUSSION  THEREOF,  AND  INDE- 
PENDENT CONTRIBUTIONS  ON  THE  SUBJECT. 


Reprinted  from  Vols.  XXVIII-XXXI  of  the  Transactions  of  the  American  Institute  of 

Mining  Engineers. 


NEW  YOKE  CITY : 

PUBLISHED  BY    THE   INSTITUTE 

AT  THE  OFFICE  OF  THE  SECRETARY. 
1902. 


t 


MIMINtf   0«PT, 


PREFACE. 


THIS  volume  contains  by  no  means  the  whole  of  the  discus- 
sion elicited  by  the  original  paper  of  Mr.  Scott.  Additional 
contributions,  received  too  late  for  introduction  here,  will  be 
found  in  the  Transactions  of  the  Institute,  to  which  the  reader 
is  referred.  This  circumstance  is,  however,  less  to  be  lamented 
than  if  it  had  been  possible,  by  a  little  longer  delay,  to  close 
the  whole  discussion,  leaving  nothing  to  be  corrected  or  added. 
But  the  subject  is  one  of  those  which  will  never  be  exhausted; 
and  there  would  be  greater  cause  for  regret  if  the  issue  of  this 
volume  should  be  construed  by  practising  mine-surveyors  and 
the  designers  or  makers  of  surveying-instruments  as  an  intima- 
tion that  further  statements  of  fact,  argument  or  criticism 
would  not  be  welcomed  by  the  Council  of  the  Institute.  I 
trust  that  such  a  misunderstanding  will  be  effectively  prevented 
by  the  appearance  in  Vol.  XXXI.  of  the  Transactions  of  the 
interesting  additional  papers  of  Mr.  II.  D.  Hoskold,  to  say 
nothing  of  minor  contributions  on  the  subject,  none  of  which 
have  been  included  in  the  present  volume. 

It  is  believed,  nevertheless,  that  the  material  here  presented 
comprises,  in  compact  and  convenient  form,  information  of 
sufficient  scope  and  value  to  warrant  the  issue  of  the  book  by 
the  Institute.  R.  W.  RAYMOND, 

Secretary. 


303741 


CONTENTS. 


PAGE 

PREFACE, iii 

The  Evolution  of  Mine-Surveying  Instruments  ;  by  Dunbar  D.  Scott,  .         .  1 

DISCUSSION  : 

Secretary's  Note,          .                                  V       ...         .         .  68 

Bennett  H.  Brough,    .         .         .         .        ......         .  68 

D.  D.  Scott,         .         .         .         .        > 71 

W.  F.  Stanley,    .         .        .        .         ...         .         .         .        .  75 

D.  D.  Scott,        .       ,...'.'      .....        .        .         .  76 

C.  L.  Berger  &  Sons,  .         .        .'        .         .        '.         .         .         .         .  77 

F.  W.  Breithaupt  &  Sohn, .      •»'.... 78 

Prof.  Dr.  Max  Schmidt, 82 

D.  D.  Scott, 86 

D.  W.  Brunton, 88 

H.  D.  Hoskold, .        .        .  91 

D.  D.  Scott, 119 

Jas.  B.  Cooper,   . 121 

W.  S.  Hungerford,      .......         ...  123 

D.D.Scott,         .       -.         .        ....      ;    '    .         .         ....  126 

J.  E.  Johnson,     .         .         .  j      ,         . 129 

Julius  Kellerschon,     .         ..;      ,       .,        ....         .         .  133 

P.  &  K.  Wittstock,      .-      .         .         .         .         .      ,*         •        •         •  13f> 

Edwin  J.  Hulbert,      .         .        .         .        .        .        ....  146 

Alfred  C.  Young,      ..         .       v.        .        .        .        .      '  .         .         .  152 

Frank  Owen,       .         .       ..    .    .        •        *        .     '  .  ..     .         .         .  164 

K.  W.  Kaymond,        .         .         .                 .         ...         .        .  166 

History  of  Solar  Surveying-Instruments  ;  by  J.  B.  Davis,    .         .         .         .  172 

Eemarks  on  Mine-Surveying  Instruments,  with  Special  Keference  to  Mr. 
Dunbar  D.  Scott's  Paper  on  their  Evolution,  and  its  Discussion  ;  by 

H.  D.  Hoskold, 206 

Notes  on  Mine-Surveying  Instruments,  with  Special  Keference  to  Mr. 
Dunbar  D.  Scott's  Paper  on  their  Evolution,  and  its  Discussion  ;  by 

Benjamin  Smith  Lyman,  ........  237 

Notes  on  Tripod-Heads,  with  Eeference  to  Mr.  Scott's  Paper,  etc.  ;  by  John 

H.  Harden, 290 

The  Evolution  of  Mine-Surveying  Instruments,  Concluding  Discussion  ;  by 

Dunbar  D.  Scott,  ..........  293 

Index, 309 

Errata, 323 


(v) 


THE  EVOLUTION  OF  MINE-SURVEYING 
INSTRUMENTS. 

BY  DUNBAR  D.  SCOTT,  PHOENIX,  MICH. 


THE  development  in  the  perfection  of  mine-surveying  instru- 
ments has  heen  by  no  means  rapid,  as  it  has  depended  some- 
what on  the  details  of  construction  borrowed  from  astronomical 
and  geodetic  theodolites,  largely  on  the  restrictions  laid  down 
by  mining  companies  and  the  prejudices  of  mine  managers 
themselves,  but  more  than  all  on  the  methods  used  in  conduct- 
ing surveys  and  the  importance  attached  thereto. 

Mine-surveying,  in  some  form  or  other,  has  been  practiced 
from  the  very  earliest  times ;  but  it  has  never  kept  pace  with 
the  other  branches  of  surveying,  or  even  with  the  art  of  min- 
ing itself,  and  cannot  be  recognized  as  an  exact  science  until 
shortly  before  the  beginning  of  this  century. 

The  works  of  Hero  of  Alexandria,  who  lived  in  the  second 
century  B.C.,  are  still  extant,  and  contain  descriptions  of  a  rec- 
tangular sighting-instrument,  which  he  invented  and  called  a 
diopter.  His  improvement  upon  this  simple  construction,  which 
possibly  he  devised  for  use  in  the  Greek  mines  for  rough  level- 
ing-purposes  and  for  laying  out  any  angle,  must  be  considered, 
says  Hiibner,*  as  the  origin  of  the  highly  perfected  theodolite  of 
to-day. 

Whether  this  instrument  came  into  general  use  during  the 
first  centuries  of  the  Christian  era,  is  not  recorded ;  in  fact,  no 
writer  undertakes  to  tell  how  mine-surveying  was  conducted 
until  1556,  in  which  year  Agricola  expounds  the  principles  of 
mining  and  metallurgy  in  his  De  Ee  Metallica,  devoting  the 
entire  fifth  chapter  to  the  practice  of  mine-surveying  (see  Fig.  1). 

In  mediaeval  times  those  who  possessed  any  knowledge  of 
engineering  skill  made  strenuous  effort  to  keep  their  art  a 
secret,  partly  on  account  of  the  miners'  proverbial  conservatism 
and  partly  for  their  own  personal  aggrandizement,  and  were,  in 

*  Mittheilungen  aus  dem  Markscheidewesen,  von  Werneke,  Freiberg,  1887. 


2  THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 

consequence,  superstitiously  regarded  as  sorcerers  of  the  kind 
who  were  expert  in  the  use  of  the  divining-rod. 

Indeed  the  superstition  of  this  period  was  so  potent  in  its  in- 

FIG.  l. 


Facsimile  from  De  Re  Metallica,  Georgius  Agricola,  Basel,  1556,  constituting  the 
frontispiece  of  Bennett  H.  Brough's  "Treatise  on  Mine-Surveying,"  London. 

1888. 

fluences  that  the  hazel-twig,  in  the  hands  of  a  sensitive  medium  r 
was  accepted  at  that  time  with  greater  confidence  than  the  most 
scientific  mathematical  deduction  then  possible. 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS.  3 

Dr.  Raymond  published,  in  1883,  a  very  complete  and  inter- 
esting paper  on  "The  Divining-Rod,*  in  which  reference  is 
made  to  all  the  best  works  on  the  subject,  both  ancient  and 
modern.  In  the  study  of  the  history  of  the  subject,  he  says : 

"  It  will  appear  that  divining-rods  were  first  used  in  antiquity  mainly  or  wholly 
for  moral  purposes ;  that  in  the  Middle  Ages  their  employment  was  for  a  long 
period  confined  to  the  discovery  of  material  objects  ;  that  towards  the  end  of  the 
seventeenth  century  the  moral  use  was  again  asserted,  and  that  in  the  eighteenth 
century  the  divining-rod  was  relegated  to  the  material  sphere  and  assumed  the 
comparative  modest  functions  in  the  discharge  of  which  it  still  lingers  among 
us."f 

And  after  showing  that  the  rod  itself  serves,  at  most,  to  ex- 
hibit the  results  of  nervous  sensibility  and  unconscious  muscular 
contraction  on  the  part  of  the  operator,  he  adds  :J 

"To  this,  then,  the  rod  of  Moses,  of  Jacob,  of  Mercury,  of  Circe,  of  Valen- 
tine, of  Beausoleil,  of  Vallemont,  of  Aymar,  of  Bleton,  of  Pennet,  of  Competti 
— even  of  Mr.  Latimer — has  come  at  last.  In  itself  it  is  nothing.  Its  claims  to 
virtues  derived  from  Deity,  from  Satan,  from  sympathies  and  affinities,  from  corpus- 
cular effluvia,  from  electricalcurrents,  from  passive  perturbatory  qualities  of  organo- 
electric  force,  are  hopelessly  collapsed  and  discarded.  A  whole  library  of  learned 
rubbish  about  it,  which  remains  to  us,  furnishes  jargon  for  charlatans,  marvellous 
tales  for  fools  and  amusement  for  antiquarians ;  otherwise  it  is  only  fit  to  con- 
stitute part  of  Mr.  Caxton's  History  of  Human  Error.  And  the  sphere  of  the 
divining-rod  has  shrunk  with  its  authority.  In  one  department  after  another  it 
has  been  found  useless.  Even  in  the  one  application  left  to  it  with  any  show  of 
reason,  it  is  nothing  unless  held  in  skilful  hands ;  and  whoever  has  the  skill  may 
dispense  with  the  rod." 

Agricola  says  the  subject  is  open  to  much  dispute ;  states  the 
evidence  on  both  sides  briefly,  but  with  admirable  clearness ; 
and,  while  he  declines  to  enter  upon  a  discussion,  "  neither  per- 
missible nor  agreeable,"  of  the  virtue  which  may  be  imparted 
to  the  rod  by  spells  and  incantations,  he  inclines  his  reader  to 
skepticism.  In  the  quaint  wood-cut  accompanying  this  chapter, 
his  "  good  and  sober  "  miners,  who  have  studied  nature,  are 
already  digging  ore,  while  the  man  with  the  rod  is  yet  pre- 
paring to  discover  it. 

Fig.  2  is  taken  from  the  Cosmographia  Univer sails  of  Sebastian 
Munster,  published  at  Basel  in  1550.  "This  geographical 
work,"  says  Dr.  H.  R.  Mill,  "  deals  only  vaguely  with  mining, 

*  Trans.,  xi.,  411.  f  Ibid.,  p.  413.  %  Ibid.,  p.  445. 

2 


FIG.  2. 


4  THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

and  I  fancy  the  cut  of  the  virgula  divina,  to  which  little  reference 
is  made,  must  have  been  copied  from  some  earlier  work." 

The  Latin  treatise  on  mining  engineering  by  J.  F.  Weidler 
(Wittenberg,  1726)  deals  at  length  with  this  supernatural 
method;  and  even  so  clever  an  engineer  as  Beyern  let  superstition 
get  the  best  of  his  mathematics.  As  late  as  1749  he  claims 
that  thorough  instruction  in  mining  engineering  involves  the 
application  of  the  divining-rod,  though  he  was  intelligent 
enough  to  insist  that,  "  if  there  is  a  difference  in  the  findings 

of  the  twig  and  com- 
pass, then  more  de- 
pendence must  be 
placed  in  the  compass 
than  in  the  twig." 

It  is  recorded  in  Chi- 
nese annals  that  in 
2364  B.C.  the  Emperor 
Hou-ang-ti,  or  Hong-Ti, 
constructed  an  instru- 
ment for  indicating  the 
South,  which,  Dr.  Gil- 
bert says,*  was  brought 
from  Cathay  to  Italy  in 
1295  by  the  renowned 
Marco  Polo.f 

F  1  a  vio  Gioj  a,  of 
Amalfi,  some  ten  or  fif- 


Ancient  Representation  of  Divining- Rod. 


teen  years  later,  was 
doubtless  the  first  Eu- 
ropean to  mount  this  magnetic  needle  in  a  box,  but  the  use  of 
the  stationary  or  Setz-compass  (Fig.  3)  in  mine-surveys  is  first 
described  in  the  work  of  Agricola. 

An  instrument  of  this  original  type,  bearing  the  date  1541, 
is  still  preserved  at  the  Neudorfer  mines  in  the  Harz.  Con- 
cerning it,  Prof.  Brathuhn  says  : 

"The  5.5  cm.  compass-box  fits  into  the  center  of  a  wooden  disk  16  cm.  in  di- 
ameter and  2  cm.  thick.  About  it  are  three  concentric  grooves  filled  with  wax  of 


*  Colcestrends  .  .  .  de  Magnete  Gulielmi  Gilberti,  London,  1600. 
f  Bailly,  Histoire  de  I' Astronomic  Ancienne,  Paris,  1775,  p.  122. 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 


FIG. 


different  colors.     Upon  the  bottom  plate  of  the  compass-box  is  drawn  only  a 

meridian    line,  marked  at  its  ends  M.   K.    (Meridies)  and  S.  P.   (Septentrio). 

When  in  use,  the  compass  and  disk 

were  put  into  the  circular  cavity 

of  a  wooden  box,  and  mounted  by 

means  of  a  hole  beneath  upon  a 

simple  staff. 

'  '  The  disk  was  turned  until  the 
needle  became  coincident  with  the 
meridian  line  ;  then  the  pointer 
that  revolved  about  its  fiducial  edge 
was  brought  into  the  direction  of 
any  course,  as  nearly  as  could  be 
judged  by  the  eye,  and  a  mark  was 
made  in  one  of  the  wax  circles  to 
indicate  its  azimuth  with  the  meri- 
dian. 

"The  course  was  then  measured 
and  recorded  with  the  character- 
ized mark  and  the  color  of  the  wax 
circle  in  which  it  was  made.  The 
survey  was  then  reproduced  on  the 
surface,  commencing  usually  at  the  mouth  of  the  shaft,  to  determine  the  prox- 
imity of  the  underground  workings  to  the  boundary  -lines." 


The  Setz-Compass. 


FIG.  4. 


Fig.  4  is  copied  from  a  drawing  of  that  period,  and  repre- 
sents an  authorized  engineer,  commissioned  hy  the  govern- 
ment of  Saxony,  engaged  in  conducting 
a  survey  with  this  instrument. 

In  another  place  in  Agricola's  work  is 
represented  a  nude  surveyor  making  ob- 
servations with  a  circle  of  wood,  nearly 
equal  in  diameter  to  his  own  height,  which 
he  holds  vertically,  and  which  is  provided 
with  a  weighted  index-pendulum. 

In  these  two  crude  yet  ingenious  ap- 
pliances we  have,  no  doubt,  the  origin  of 
the  Hangcompass  und  Gradbogen  that  came 
so  universally  into  use  throughout  the 
mining  districts  of  Europe. 

In  1571  Thos.  Diggs,  the  son  of  Leon- 
hard  Diggs,  published  in  England  his 
Pantometria,  in  which  are  described  sev- 
eral instruments  for  surveying  purposes.  His  masterpiece  is 


Surveying  with  the 
Setz-Compass. 


6  THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 

what  he  called  the  theodolitus  (Fig.  5),  perhaps  derived  from 
theodiccea,  taken  in  the  sense  of  perfection,  as  being  a  most  per- 


FIG.  5. 


Diggs's  Theodolite. 

feet  instrument.*     In  the  27th  chapter,  called  Longimetria,  he 
says : 

"It  is  but  a  circle  divided  into  360  grades  or  degrees,  or  a  semicircle  parted  into 
180  portions,  and  every  of  those  divisions  in  3,  or  rather  6,  smaller  parts.  .  .  . 
The  index  of  that  instrument,  with  the  sights,  etc.,  are  not  unlike  to  that  which 
the  square  hath  :  In  his  backe  prepare  a  vice  or  scrue  to  be  fastened  in  the  top  of 
some  staffe,  if  it  be  a  circle,  as  heere  :  let  your  instrument  be  so  large  that  from 
the  center  to  the  degrees  may  be  a  foote  in  length,  more  if  ye  list,  so  that  you  not 
erre  in  your  practices." 

For  steep  upward  sighting,  he  used  an  artificial  horizon. 
In  the  same  year  Diggs  published  his  Sfratiaticus,  in  which 
he  says  that  while  he  had  access  to  certain  of  Roger  Bacon's 

*  This  derivation  is  given  by  Stanley  in  his  work  on  Surveying  Instruments. 
Bauernfeind  says  (vol.  i.,  p.  288):  "  It  cannot  be  said  with  certainty  how  the  word 
'  theodolite,'  as  applied  to  angle-measuring  instruments,  originated.  It  was  used 
in  England  as  early  as  the  sixteenth  century,  and  probably  had  its  origin  there. 
Prevailing  opinion,  formerly,  assigned  its  derivation  to  two  or  three  Greek  words, 
one  of  which  was  Ai'So?  (stone),  and  basing  it  upon  this  derivation  the  word  should 
be  written  theodotith.  But  more  recent  archaeological  research  proves  that  any 
attempt  to  associate  the  word  as  we  now  have  it  with  the  Greek  is  a  mistake,  as 
it  is  more  probably  a  corruption  of  '  the  alidade '  by  the  English  from  al'idade, 
the  Arabic  term  applied  to  the  radius  of  the  astrolabium." 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 


unpublished  MSS.  lie  discovered  a  letter  from  his  father,  de- 
scribing a  method  of  "  viewing  distant  objects  by  placing 
perspective-glasses  at  due  intervals."  This  was  certainly  an 
application  of  the  principles  of  the  telescope,  which  he,  no 
doubt,  like  others,  had  discovered  by  personal  research  and 
experiment. 

The  period  of  the  casual  invention  of  the  telescope  is  in- 
volved in  some  obscurity.  Though  there  is  ample  evidence 
that  the  ancients  of  Ovid's  time  knew  something  of  it,  its  in- 
troduction as  a  philosophic  instrument  probably  belongs  to 
Friar  Bacon,  who  conducted  his  experiments  in  Paris,  and  died 
at  Oxford  in  1294.  Its  construction  and  uses  were  handed 
down  through  the  generation^  as  a  secret,  like  all  other  "  works 
of  iniquity "  that  aimed  at  an  advance  in  science.  Later,  in 
1590,  when  Jensen,  the  spectacle-maker,  showed  his  improved 
instrument  to  Prince  Maurice,  he  was  required,  under  severe 
penalty,  to  divulge  no  information  concerning  it,  so  that  only 
the  prince  should  be  aided  by  it  in  his  warfares ;  but  Galileo, 
having  had  it  described  to  him  in  1608,  constructed  at  Padua 
a  telescope  of  three  diameters'  power,  and  presented  it  to  the 
Doge  of  Venice.  It  was  not  until  about  this  year  that  the  op- 
ticians of  Holland  made  the  prac- 
tical application  of  the  telescope 
possible,  and  inaugurated  a  new 
era  in  the  science  of  astronomy. 

The   first   systematic   and   ex- 
clusive treatise  on  mining  engi- 
neering was   the  Geometria  Sub- 
terranea  of  Nicholas  Yoigtel  (Eis- 
leben,   Saxony,   1686),  in  which 
the  methods  and  instruments  de- 
scribed exhibit,  after  a  lapse  of 
130  years,  a  natural  development 
yet  small  improvement  over  those 
of  Agricola.     In  fact,  mine-sur- 
veys were  conducted  on  the  con- 
tinent, and  probably  also  in  England,  by  Agricola's  primitive 
means,  until  Balthazar  Eossler,  in  1633,  invented  the  method 
of  suspending   from  a  taut   hempen   cord  a  gimbal-compass 
(Fig.  6)  and  clinometer,  by  which  the  magnetic  bearing,  incli- 


FIG.  6. 


8  THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

nation  and  length  of  any  course  were  at  once  determined  with 
comparative  ease.*  The  accuracy  of  this  system,  which  Yoigtel 
describes,  depended  largely  upon  the  perfection  of  graduation, 
the  precision  possible  in  reading  the  clinometer,  the  catenary 
curve  of  the  cord  on  long  courses  (augmented  by  the  weight 
of  the  instruments  hung  upon  it),  and  the  surrounding  at- 
tractive influences  upon  the  magnetic  needle;  but  it  is  certainly 
the  first  method  for  the  determination  of  the  angular  value  of 
precipitous  grades  without  correction  for  mechanical  imperfec- 
tions in  the  apparatus. 

In  1681  Thomas  Houghton  published  a  small  treatise  upon 
subterraneous  surveying  in  the  Derbyshire  mines,f  in  which  he 
described  a  use  of  strings,'  plumbs  and  compass  very  similar 
to  the  method  of  Rossler,  except  that  the  dial,  in  a  long  rec- 

FIG.  7. 


Surveying  by  Rossler' s  Method. 

tangular  box,  was  applied  by  hand  to  the  side  of  a  string,  held 
by  two  persons,  and  afterwards  measured  with  a  rule. 

The  method  of  Rossler,  or  some  adaptation  of  it,  prevailed 
throughout  Europe  with  remarkable  tenacity  up  to  the  begin- 
ning of  this  century ;  and  even  to-day,  at  some  mines,  no  other 
instruments  are  used ;  while  at  others  the  use  of  these,  in  con- 
junction with  the  theodolite,  is  not  infrequent.  For  about  eighty 
years  the  prestige  of  the  method  was  undisputed,  though  it 
underwent  various  modifications  to  suit  the  conditions  of  prac- 
tice. Hempen  cords  gave  way  to  brass  chains;  but  these  (like 
Gunter's,  of  1620,  which  was  substituted  for  Houghton's  rule  in 
English  collieries)  were  found  to  elongate  by  tension  and  fric- 
tion, so  that  frequent  adjustment  became  necessary.  The  cat- 
enary curve  of  the  cord,  chain  or  wire  was  always  a  matter  of 

*  Die  Entwickdung  der  Markscheidekunst,  M.  Schmidt,  Freiberg,  1889. 
f  Rara  Avis  in  Term,  T.  Houghton,  London,  1681. 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS.  9 

perplexity  until  about  30  years  ago,  when  Prof.  A.  von  Miller- 
Hauenfels,  of  Vienna,  deduced  rules  for  the  suspension  of  the 
clinometer  in  positions  to  indicate  the  exact  grade  between 
the  two  stations. 

In  1775  Hofrath  Kastner  designed  a  quadrant-clinometer, 
which  was  suspended  from  the  ends  of  an  index-arm  bearing 
a  vernier-scale.  The  plummet  was  still  used,  but  only  for  the 
purpose  of  insuring  the  verticality  of  the  zero-point.* 

In  1877  Schneider  designed  a  complete  circle  of  aluminum, 
dispensing  with  the  plummet  entirely,  and  substituting  an  ali- 
dade with  opposite  verniers,  the  verticality  of  which  was  deter- 
mined by  a  bubble  on  its  lower  arm.f 

The  hanging-compass  also  underwent  various  reforms  in 
fruitless  attempts  to  employ  it  successfully  in  the  presence  of 
iron.  Up  to  1749  it  had  not  been  materially  changed  from  its 
original  construction.  The  works  of  both  A.  Beyer,  of  Alten- 
berg,  and  F.  W.  von  Oppel,  of  Dresden,  published  in  that  year, 
contained  nothing  new  in  instrumental  construction ;  but  each 
introduced  the  use  of  sines  and  cosines  in  the  calculations. 

In  the  second  edition  of  Beyer's  work,  as  revised  by  Lempe 
in  1785,  appeared,  for  the  first  time,  an  illustration  of  the  now 
common  form  of  hanging-compass  (see  Fig.  7),  said  to  have 
been  made  by  Schubert  of  Freiberg. 

The  most  notable  modifications  of  this  instrument  are  com- 
paratively recent,  and  include  the  adjustable  forms  of  Brauns- 
dorpf  (1834),  Lendig  (1846),  Reichelt  (1856),  Osterland  (1860), 
Lehman  (1873),  Plamineck  (1878),  Fuhrmari  (1879),  and  Penk- 
ert  (1880). 

In  the  earliest  times  mine-plans  were  rare  and  rude.  The 
object  of  most  surveys  was  to  retrace  on  the  surface  the  contour 
of  a  subterranean  opening.  "  Underground,"  says  Houghton, 
"  the  dial  is  guided  by  the  string,  but  on  the  surface  the  string 
is  guided  by  the  dial."  But  as  the  importance  of  maps  became 
more  obvious,  the  hanging-compass  was  so  modified  that  the 
compass-box  might  be  removed  and  transferred  to  a  brass  pro- 
tractor-plate, where  it  was  clamped  in  exact  position,  and  the 
survey  was  plotted  with  the  same  instrument  used  in  making 

*  Lehrbuch  der  Praktischen  Markscheidekunst,  O.  Brathuhn,  p.  34. 
f  Oesterr.  Zeitsch.  filr  Berg-  und  Huttenwesen,  1877,  p.  367. 


10 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 


FIG.  8. 


it.  This  method  is  described  in  the  first  edition  of  Voigtel's 
work  (Eisleben,  1686),  and  is  also  spoken  of  in  The  Exact  Sur- 
veyor by  J.  Eyre  (London,  1654)  as  though  it  had  been  cus- 
tomary many  years  previously.  Describing  the  circumferenter 
of  that  day,  Eyre  says : 

' '  For  portability  this  instrument  exceedeth  any  other,  and  is  usually  made  of 
wood,  containing  in  length  about  eight  Inches,  and  in  breadth  about  four  Inches, 
and  in  thicknesse  three  quarters  of  an  Inch,  the  left  side  whereof  is  divided  into 
divers  equall  parts,  most  fitly  of  twelve  in  an  Inch,  to  be  used  as  a  scale  of  a  pro- 
tractor, the  Instrument  of  itself  being  fitting  to  protract  the  plat  on  paper  by  help 
of  the  Needle,  and  the  degrees  of  Angles,  and  length  of  Lines  taken  in  the 
Field." 

The  idea  is  creditable ;  but  its  benefits  are  questionable,  in 
view  of  the  fact  that  the  magnetic  influences  are  not  the  same 

in  the  office  as  in  the  mine. 
Moreover,  for  plotting-purposes, 
the  delicacy  of  a  3-inch  needle 
in  a  circle  graduated  to  only  J° 
is  not  beyond  reproach.  Since 
1801,  the  protractor-plate  itself 
has  been  so  provided  with 
adjustable  tangent- semicircles 
(see  Fig.  8)  that  it  could  be  used 
for  both  purposes ;  but,  though 
widely  used  by  mining-captains 
in  Germany,  it  does  not  permit 
very  accurate  work. 

The  constancy  of  the  mag- 
netic needle  has  been  questioned 
only  in  times  which  must  be  considered  as  recent,  compared 
with  the  long  period  of  its  use ;  but  long  before  angular  or  trigo- 
nometrical surveying  had  been  presented  as  the  only  rational 
method,  the  variable  susceptibility  of  the  needle  to  magnetic 
influences  had  been  the  subject  of  investigation  and  discussion 
important  to  the  mining  engineer,  who  had  no  alternative  in 
localities  of  strong  attraction  but  the  use  of  the  very  instrument 
most  affected  thereby.  The  earliest  astronomical  observations 
to  determine  the  secular  variation  were  made  in  Paris  in  1541, 
when  the  needle  pointed  7°  E.  of  N".  By  1580  it  had  reached 
a  maximum  of  11°  80',  when  it  began  to  recede,  reaching  the 


The  Compass- Protractor  afc  used  for 
Mine-Surveys. 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS.  11 

true  meridian  in   1666.     The  yearly  variation  then   became 
westward  until  1814,  when  a  maximum  of  22°  34'  was  attained  ! 
Bennett  H.  Brough  says  : 

"  There  can  be  no  doubt  that  in  times  past  a  neglect  of  this  variation  has  led 

to  errors  involving  great  loss  and  serious  danger Regular  observations 

were  not  made  until  the  middle  of  the  seventeenth  century ;  but  there  is  a  pas- 
sage (which,  however,  is  so  obscure  that  its  meaning  is  doubtful),  apparently  re- 
ferring to  the  declination  of  the  needle,  in  the  oldest  treatise  on  mining,  an  ex- 
tremely scarce  work,  written  in  German  and  published  in  1505.  No  copy  of  the 
first  edition  of  this  '  well  arranged  and  useful  little  book,'  as  the  anonymous  author 
calls  it,  is  known  to  exist." 

In  1763  Isaac  Prince,  of  Bonsai,  in  his  Miner's  Guide  or  Com- 
plete Miner,  says,  with  respect  to  magnetic  surveying : 

11  The  knowledge  of  ye  quantity  of  this  Declination,  which  is  pretty  near  ye  same 
one  year  as  another  and  sometimes  differs  very  little  for  many  years  together, 
enables  us  to  adjust  ye  Needle  in  such  a  manner  as  if  it  had  no  Inclination  at  all. 
Though  ye  knowledge  of  this  Inclination  has  hitherto  been  fruitless,  it  is  to  be 
hoped  yt  some  time  or  another  some  advantage  or  profit  may  be  discovered  by  its 
regularity."* 

Annual  and  diurnal  variations  were  also  studied  and  dealt 
with  as  intelligently  as  the  time  and  place  permitted ;  but 
general  efforts  to  remedy  the  er- 
ratic and  deceptive  demeanor  of  FlG- 
the  needle  in  the  presence  of  iron 
finally  resulted  in  the  invention 
and  introduction  in  Germany  of 
the  Eisenscheibe  or  iron  disk. 
The  first  forms  of  this  instru- 
ment were  described  in  the  third 
edition  of  Yoigtel  (1713),  though 
L.  C.  Strum,  of  Frankfort,  had 
proposed  the  use  of  the  astrola- 
bium  for  the  miner  as  early  as 
ITlO.f  Fig.  9  represents  the  de- 
sign  of  J.  G.  Studer,  of  Freiberg, 

which  is  somewhat  of  an  improvement  over  the  original  forms, 
though  its  principal  features  are  the  same.  The  disk,  as  will 
be  noticed,  was  graduated,  like  the  compass  of  that  day,  into 

*  Quoted  from  Cantor  Lectures  on  Mine-Surveying,  B.  H.  Brough,  London,  1892, 
p.  9,  in  Surveying  by  the  True  Meridian,  E.  W.  Newton,  F.G.S.,  Falmouth,  1895. 
f   Vier  Kurz  Abhandlungen,  Leon.  Chr.  Strum,  Frankfurt,  1710. 


12  THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

twenty-four  hours,  the  twelfth  hour  marking  the  !NT.  and  S. 
cardinal  points.  In  conducting  a  survey  by  its  use,  two,  and 
preferably  three,  instruments  were  employed;  one  being  set 
up  at  each  adjacent  station.  The  indicator-arms  were  then 
tied  together  with  a  stout  cord,  first  on  one  side,  then  on  the 
other,  observing  the  interior  angles.  In  the  same  way  the 
angles  of  inclination  on  the  vertical  arc  were  noted  ;  and  then 
the  last  instrument  was  brought  forward  to  establish  a  new 
station.  Later,  each  hour  was  subdivided  into  fifteen  equal 
parts,  so  that  each  division  corresponded  to  a  degree  of  the 
sexagesimal  system,  making  it,  as  compared  with  the  compass, 
a  most  reliable  instrument  for  this  work ;  indeed,  it  is  con- 

FIG.  10.  FIG.  11. 


Modern  Swedish  Mine-Tripod  and  Alidade. 

sidered  by  German  authorities  to  be  the  predecessor  of  the  per- 
fect mine-theodolite  now  in  general  use. 

The  same  feeling  seems  to  have  prevailed  also  in  Sweden, 
where  we  find  mining  engineers,  near  the  beginning  of  the 
nineteenth  century,*  discarding  the  compass  entirely  in  their 
magnetic  iron-mines,  and  substituting  the  graphic  method  of 
conducting  mine-surveys  by  plane-tables  of  a  peculiar  make, 
which,  with  rare  exceptions,  has  been  in  use  ever  since. 

The  invention  of  the  plane-table  is  generally  attributed  to  Prae- 
torius  in  1537;  but  Leonhard  Zubler,  in  the  first  published  ac- 
count of  it  (1625),  credits  its  origin  to  Eberhard,  a  stone-mason. 

*  Handladning  uti  Svemka  Markscheidereit,  Horneman,  Stockholm,  1802  ;  also, 
Reise  durch  Skandinavien,  J.  F.  L.  Hausrnann,  Gottingen,  1811-19,  vol.  v.,  pp.  115- 
126. 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS.  13 


"Who  introduced  it  into  Sweden  for  mine-surveys,  Prof. 
denstrom  is  unable  to  determine;  but  the  earliest  instruments, 
no  doubt,  were  of  rude  construction,  with  only  a  sighted  ali- 
dade. I  present  here  (Figs.  10  and  11)  a  modern  tripod,  show- 
ing the  clamping-ring  by  which  the  paper  is  held  in  position 
while  receiving  the  plot.  The  telescopic  alidade  does  not  differ 
from  those  in  general  use  in  other  countries  for  surface-work, 
except  that  its  vertical  circle  is  full,  reading  to  minutes,  and  the 
base-rule  that  carries  the  bubbles  has  the  linear  subdivisions 
engraved  along  the  edge. 

The  Rapid  Traverser  of  Henderson,  of  Truro,  Cornwall,  in- 
troduced in  1892,  is  very  similar  to  this  mode  of  construction, 
except  that  its  alidade  is  pivoted  at  the  center,  instead  of  being 
free  to  move  in  any  position.  The  survey  cannot  be  plotted  in 
the  field,  as  by  the  Swedish  method.  Disks  of  celluloid,  or  pref- 
erably white  enameled  zinc,  are  employed,  and  the  direction 
of  each  course  or  draught  is  marked  upon  one  of  the  five  con- 
centric circles  engraved  upon  its  surface.  This  instrument  and 
method,  it  seems,  will  eventually  supersede  in  Cornwall  such 
magnetic  surveys  as  caused  the  recent  casualty  in  Wheal 
Owles  mine  at  St.  Just. 

The  magnetometer  of  Prof.  Robert  Thalen  of  Upsala  and 
that  of  Tiberg  are  the  only  other  Swedish  instruments  that 
have  come  to  the  writer's  notice.  Thalen's  is  called  a  simplified 
modification  of  the  magnetic  theodolite  of  Dr.  Lamont;*  but 
in  reality  the  association  is  very  remote,  consisting  only  in  the 
so-called  sinus-method  of  using  it,  which  has  been  borrowed 
from  Lamont.  f  It  is  a  simple  compass-instrument,  having  a 
magnet  upon  an  arm  in  the  line  of  sight,  so  arranged  that,  by 
its  application  and  removal  at  the  proper  time,  the  azimuth  of 
each  course  is  obtained. 

Tiberg's  (1880)  is  almost  identical  with  this,  except  that  the 
compass-box  is  set  in  bearings  upon  low  standards,  and  occa- 
sionally made  to  revolve  in  a  vertical  position  for  use  as  a  dip- 
needle,  in  determining  the  location  of  magnetic  ore-deposits. 

In  Warmlander  Annaler  of  1888,  Mr.  Sjogren  describes  some 

*  L'  Industrie  Miniere  de  la  Suede,  G.  Nordenstrom,  p.  22.  (A  translation  of  the 
methods  here  described  occurs  in  Mines  and  Minerals,  Scranton,  Pa.,  November, 
1898.) 

f  Sur  la  recherche  des  Mines  defer  a  Vaide  de  mesures  magnetiques,  E.  Thalen,  1877. 


14 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


very  creditable  work  of  this  kind,  done  with  Tiberg's  instru- 
ment at  Persberg. 

In  England  the  magnetic  needle  and  Houghton's  methods 
were  adhered  to,  amid  recurring  failures  and  disasters,  with  a 
loyalty  that  prevails  even  to-day  in  some  parts  of  Cornwall.* 

In  1778  Dr.  W.  Pryce  declared  that  methods  similar  to 
Houghton's  were  still  in  vogue,  f  He  says : 

FIG.  12. 


Old  English  Miners'  Dial. 

* '  The  instruments  used  are  a  compass  without  gnomon  or  style  but  a  center- 
pin  projecting  from  the  center  of  the  compass  to  loop  a  line  to,  or  stick  a  candle 
upon,  fixed  in  a  box  exactly  true  and  level  with  its  surface,  about  6,  8  or  9  inches 
square,  nicely  glazed  with  a  strong  white  glass,  and  a  cover  suitable  to  it  hung 
square  and  level  with  the  upper  part  of  the  instrument ;  a  24-inch  gauge 
or  two-foot  rule  and  a  string  or  small  cord  with  a  plummet  at  the  end  of  it ;  a 
little  stool  to  place  the  dial  horizontally  ;  and  pegs  and  pins  of  wood,  a  piece  of 
chalk,  and  pen,  ink  and  paper." 

Later  (about  1785),  extended  sights  were  added;  the  little 
three-legged  stool  no  doubt  became  the  tripod  ;  and,  with  one 
or  two  other  slight  improvements,  we  have  in  England,  just 

*  Proc.  Royal  Cornwall  Polyt.  Soc.,  1893. 

f  Mineralogia  Cbrnubiensis,  W.  Pryce,  London,  1778,  pp.  202-213. 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


15 


FIG.  13. 


before  the  beginning  of  this  century,  the  type  of  dial  shown  in 
Fig.  12,  in  a  modernized  form,  as  made  by  W.  F.  Stanley,  of 
London.  "Who  is  responsible  for  its  conception  as  a  whole  is 
not  known — probably  no  one  particular  person,  as  too  many 
years  were  required  to  bring  it  to  even  its  original  simple  con- 
struction ;  but  Adams  must  have  im- 
proved upon  it;  since  an  instrument 
similar  to  this  is  described  in  his  Geomet- 
rical Essays  of  1803.  It  originally  had 
no  bubbles,  but  was  considered  level 
when  the  needle  floated  freely. 

The  early  makers  were,  however,  in 
the  habit  of  partly  counter-sinking  two 
spirit-levels  in  the  compass-box  if  de- 
sired ;  but  these  were  not  recommended, 
because,  by  reason  of  their  small  size, 
they  were  seldom  accurate,  and  the  ope- 
rator could  not  test  them,  or  even  adjust 
them  if  they  were  known  to  be  untrue. 

In  the  English  dial  shown  in  Fig.  12 
the  socket  is  slotted  down  on  one  side 
(F)  so  as  to  permit  the  limb  to  be  turned 
vertically,  making  the  sights  horizontal. 
In  this  position,  after  the  long  bubble 
beneath  the  compass  is  made  level,  the 
compass-box  cover  is  adjusted  and  the 
very  small  plummet,  suspended  from  its 
top  by  a  hair  or  silk  thread,  is  made  to 
read  zero  on  the  graduations.  The  sights 
can  then  be  tipped  up  or  down,  and  gra- 
dients up  to  45°  can  be  determined  ap- 
proximately. It  will  be  noticed  that  the  graduated  cover,  as  in 
most  other  English  dials,  has  the  correction  for  declivity  marked 
upon  it,  so  as  to  save  the  operator  any  calculation  in  this  par- 
ticular. Lean  began  this  practice  in  Cornwall  in  1825,  receiv- 
ing a  prize  of  thirty  guineas  for  his  borrowed  improvement. 

In  1798  H.  C.  W.  Breithaupt,  of  Cassel,  introduced  an  instru- 
ment which  may  be  justly  designated  the  first  of  mine-theodo- 
lites. Fig.  13  is  reproduced  from  the  original  drawings  of  the 
inventor  by  the  courtesy  of  his  heirs,  F.  W.  Breithaupt  &  Son. 


Breithaupt' s  First  Mine- 
Theodolite. 


16 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


FIG.   14. 


In  his  book,*  Herr  Breithaupt  described  the  use  of  this  instru- 
ment in  a  new  system  of  surveying,  which  he  himself  first  prac- 
tised in  the  Reichelsdorfer  copper-mines  of  Hesse. 

Jesse  Bamsden  had  already  (1760)  constructed  a  circular 
dividing-engine  in  London,  in  response  to  the  urgent  demands 
of  geodetic  engineers  for  circles  of  greater  accuracy  than  those 
heretofore  graduated  by  hand;  and  M.  Pierre  Vernier,  of  Bur- 
gundy, had  long  since  (1631)  published  in  Brussels  a  descrip- 
tion of  the  micrometer-scale  which  now  bears  his  name.  We 
must  note  here,  parenthetically,  that  Vernier's  scale  was  ad- 
justed by  hand  until  Helvetius,  the  cele- 
brated astronomer  of  Danzig,  invented, 
about  1650, the  clam p-and-tangent move- 
ment. Applying  these  precedents,  Breit- 
haupt circumscribed  a  compass  with  a 
carefully  divided  circle,  read  by  Ver- 
nier-plates; invented  an  arrester  that 
should  clamp  the  needle  when  not  in 
use ;  superimposed  an  adaptation  of  the 
clinometer  that  was  surmounted  by  a 
sighting-tube;  and  supported  this  com- 
pact combination  upon  a  sort  of  tele- 
scopic tripod-stand,  which  could  be  ad- 
justed for  height  by  means  of  set-screws 
at  the  side. 

Instead  of  using  two  or  more  instru- 
ments, as  was  customary  in  employing  the  Eisenscheibe,  he  de- 
signed a  signal-lamp,  two  of  which  were  used  interchangeably 
with  the  instrument.  These  instruments,  which  sold  for  8 
carolin  ($33.70),  he  made  himself,  and  felt  the  necessity  of 
economy  so  strongly  that  he  made  a  plain  sighting-tube  to  take 
the  place  of  a  telescope. 

In  the  same  year  Prof.  Guiliani,  of  Vienna,  constructed  a 
mine-instrument  which  he  called  a  Katageolabium.  Like  the 
Graphometer  Souterrain  of  Gen.  Komarzewski,  it  was  closely 
allied  to  the  Eisenscheibe. 

In  England  the  same  spirit  of  economy  and  consequent 
simplicity  of  construction  has  always  prevailed.  In  1796 


The  Jones  Circumferenter. 


Besehr'eibung  eines  neuen  Markscheidinstruments,  Kassel,  1800. 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS.  17 

W.  &  S.  Jones,  of  London,  introduced  a  circumferenter  (Fig.  14), 
which,  in  addition  to  the  ordinary  compass,  was  provided  with 
a  10-inch  brass  circle,  divided  into  single  degrees  and  read 
by  the  " nonius"  as  they  were  then  called  in  England,  to  5 
minutes  of  arc.  In  offering  this  instrument  to  the  engineering 
profession,  Mr.  Jones  said :  "  The  error  to  which  an  instrument 
is  liable,  where  the  whole  dependence  is  placed  on  the  needle, 
soon  rendered  some  other  invention  necessary  to  measure 
angles  with  accuracy ;  among  these  the  common  theodolite, 
with  four  plain  sights,  took  the  lead,  being  simple  in  construc- 
tion and  easy  in  use."* 

It  was  fitted  with  one  pair  of  fixed  and  one  pair  of  movable 
sights,  like  Henderson's  dial 
(1869),  and  "marks  the  date," 
says  Mr.  Newton,  "  of  the  first 
attempt  in  England  to  conduct 
underground  surveys,  in  the 
presence  of  iron,-  with  any  de- 
gree of  accuracy." 

Elliott  Bros,  made  such  an 
instrument  for  Fen  wick  in 
1822,f  but  on  account  of  its 
expense  this  construction  was 
not  much  used  until  Lean  began 
to  employ  vernier  -  circles  in 
1836  in  the  Cornish  mines. 

So   far   as    available    evidence   Simple  English  Theodolite  of  last  Cen- 

can  be  relied  upon,  what  is  now       tnr^  now  commonly  known  as  Lean's 

T  Dial. 

commonly   known   as    "  Lean  s 

dial"  was  the  first  telescopic  mine-instrument  ever  introduced; 
but  there  is  some  doubt  concerning  this  fact.  Fig.  15  is  taken 
from  the  Geometrical  and  Graphical  Essays  of  George  Adams, 
published  in  1797.  It  is  there  said  to  be  intended  as  a  fair  sort 
of  cheap  theodolite.  Lean's  grandson  can  furnish  no  authentic 
information;  but  it  is  known  that  when  it  was  first  used  in  mine- 
surveys,  and  made  for  Captain  Lean  by  the  Wilton  Works  of  St. 
Day,  the  vertical  arc  and  telescope  were  removed  for  common 
sights  and  replaced  only  for  surface-work.  In  accordance  with 

*  Adams's  Geometrical  Essays,  revised  by  Jones,  London,  1797,  p.  223. 
f  Treatise  on  Mathematical  Instruments)  J.  F.  Heather,  London,  1849. 


18 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


FIG.  16. 


the  prevailing  custom,  the  sights  alone  were  used  underground. 
The  dial  was  set  up  only  at  alternate  stations ;  the  back-  and 
fore-sights  were  read  with  the  needle ;  and  the  bearings  were 
assumed  to  be  correct.  The  centers  of  vertical  shafts  simply 
became  intermediate  stations;  but  if  an  inclined  shaft  was 
encountered,  a  cross-staff  was  set  up  in  it,  so  that  one  pair  of 
sights  were  directed  at  a  candle-light  in  the  bottom ;  then  the 
dial  was  set  up  in  a  drift  and  made  to  bear  upon  the  other  pair. 
In  this  way  the  magnetic  bearing  of  the  shaft  was  calculated 
by  adding  or  subtracting  90°.  "Many  miles  of  dialing  have 
been  done,"  says  Franklands,  "  by  this  rapid  but  blindfold 
method,  with  no  means  of  closing  the  survey."  It  was  not 

thought  possible,  at  that  time, 
to  connect  the  surface  and 
underground  surveys  by  any- 
thing but  magnetic  bearings, 
so  that  the  telescopic  attach- 
ment to  the  so-called  Lean 
dial  can  hardly  be  consid- 
ered the  antecedent  of  Breit- 
haupt's  first  telescopic  mine- 
transit  (made  in  183  2),  though 
it  has  been  widely  used  in 
more  recent  years  for  such 
purposes.  Since  1871,  E.  T. 
Newton  &  Son,  of  Cam- 
borne,  have  made  the  Y's  of 
the  telescope  interchange- 
able with  the  arc  or  the  sights.  By  thus  mounting  the  tele- 
scope upon  the  limb  just  over  the  compass-box,  the  instrument 
becomes  a  substitute  for  the  Gravatt  level,  which  has  found 
great  favor  in  the  English  colonies. 

It  is  a  recorded  fact  that  the  general  design  of  this  dial  came 
from  the  standard  model  English  theodolite,  to  which  it  bears 
a  strong  resemblance.  This  instrument  is  rarely  used  in  Eng- 
lish collieries  on  account  of  its  cost;  but  its  construction  has 
long  since  been  such  that  vertical  sights  from  one  side  were 
possible.  The  prolongation  of  an  inclined  shaft  alignment, 
however,  can  be  accomplished  only  by  reversing  the  telescope 
in  its  bearings  or  by  revolving  180°  upon  its  horizontal  limb. 


Seven-inch  English  Theodolite  of  Last 
Century. 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS.  19 

Why  it  is  that  English  engineers  adhere  to  this  model  has 
always  been  a  source  of  wonder  to  the  American  profession ; 
for,  in  the  relationship  of  the  telescope  to  the  vertical  circle,  it  is 
one  of  the  most  extreme  of  eccentric  types.  Its  retention, 
however,  must  be  well  merited,  or  it  would  have  been  sup- 
planted by  the  transit-principle  of  Ramsden  in  1803,  or  by  the 
concentric  model  of  Sir  George  Everest  (1837),  which  practi- 
cally became  obsolete  twenty  years  ago.  But  whatever  it  has 
to  commend  or  to  disqualify  it,  the  important  developments  in 
English  engineering-instruments  must  be  followed  witb  this 
theodolite.  In  Gardener's  Practical  Surveyor  (1737)  we  have  de- 
scriptions of  this  theodoliter  much  improved  and  brought  to 
nearly  its  present  form  by  Jonathan  Sissons,  an  optician  of 
London  (Fig.  16).*  It  was  not  perfected,  however,  until  1760, 
when  Ramsden  sensitized  its  graduated  u  brain,"  and  John 
Dolland  sent  pure  light  coursing  through  its  telescopic  "  sonl." 
Dolland  discovered  the  construction  of  an  achromatic  telescope 
in  a  compound  objective  of  two  kinds  of  glass  (in  direct  antago- 
nism to  the  principles  laid  down  by  Sir  Isaac  Newton),  by 
which  both  spherical  aberration  and  errors  arising  from  varying 
refrangibility  were  in  a  great  measure  overcome.  While  this 
discovery  was  very  important  in  the  manufacture  of  geodetic 
and  astronomical  instruments,  "  the  most  perfect  objectives 
were  not  made,"  says  Thomas  Dick,  "  until  after  the  improve- 
ments of  Dr.  Blair,  of  Edinborough,  Rodgers,  of  London,  and 
Fraunhofer,  of  Munich,  in  the  first  quarter  of  this  century  "f — 
just  before  telescopic  instruments  came  into  general  use  for 
mine-work. 

Lean's  dial,  then,  might  have  had  a  practically  achromatic 
telescope.  It  might  also  have  been  provided  with  a  diaphragm 
and  cross-hairs;  for  Huygens  discovered  that  any  object  placed 
in  the  mutual  focus  of  the  two  lenses  of  a  Kepler  telescope 
(1611)  appeared  as  distinct  and  well  defined  as  any  distant 
body.  Following  this  established  theory,  in  1669  Jean  Picard, 
Marquis  Malvasia  and  others  crossed  silken  fibers  in  the  mutual 
focus  of  their  astronomical  instruments ;  and  these,  while  gen- 
erally acknowledged  to  be  too  large  for  the  work  required,  were 

*  This  particular  figure  represents  an  instrument  made  by  Kamsden,  Jones, 
Adams,  and  others,  after  the  general  style  of  Sissons. 

f  The  Practical  Astronomer,  Thomas  Dick,  LL.D.,  New  York,  1846. 

3 


20 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 


FIG.  17. 


Modern  English  Theodolite. 


used,  in  lack  of  something  better,  for  a  century  or  more.  In 
1755  Prof.  Fontana,  of  Florence,  proposed  the  use  of  spider- 
webs,  though  it  is  said  they  were  not  put  into  practical  use 
until  Troughton  secured  for  this  purpose  the  webs  of  the  geo- 
metrical spider,  at  the  in- 
stance of  David  Bitten- 
house,  of  Philadelphia,  who 
was  then  constructing  the 
first  American  telescope. 

At  the  time  the  telescope 
begins  to  play  some  part 
in  the  construction  of  min- 
ing instruments  we  find  it, 
so  far  as  possibilities  are 
concerned,  a  very  perfect 
device;  but  as  the  use  of 
fine-quality  lenses  entailed 
considerable  extra  expense, 
and  as  almost  any  contri- 
vance was  considered  good 
enough  for  surveys  in  dirty  little  underground  passages,  we 
find  at  that  time  generally  only  poor-quality  and  low-power 
telescopes  in  use. 

For  the  precise  shaft-  and  tunnel-work  involved  in  the  con- 
struction of  the  Great  Western  Eailway 
in  1843,  Bourne  was  probably  first  to  use 
the  high-class  English  theodolite,  shown 
in  Fig.  17,  in  connecting  the  underground- 
and  surface-surveys  through  the  vertical 
shafts. 

Since  that  time,  and  doubtless  before  it, 
the  ideal  instrument  for  nadir-sighting  has 
been  considered  one  in  which  the  vertical 
axis  of  the  concentric  type  should  be  en- 
larged and  perforated  sufficiently  to  per- 

observations. 

R  Hassler,  Superintendent 
of  the  U.  S.  Coast  Survey,  designed  such  an  instrument  (Fig. 
18),  which,  as  subsequently  improved  by  General  Ibanez,  was 
pronounced  by  the  European  Degree-Measuring  Commission  to 


FIG.  18. 


Hassler's  Instrument  with 
Perforated  Vertical  Axis. 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 


21 


FIG.  19. 


be  perfect  for  the  purposes  intended.*  It  had  two  slow,  inde- 
pendent lateral  motions,  like  the  sliding  stage  of  a  microscope, 
by  which  the  cross-hairs  could  be  brought  exactly  over  a  point 
in  the  aligned  base-line  to  insure  perfect  parallelism  in  the  sub- 
sequent setting  of  the  metallic  measuring-rod.  As  its  use  was 
restricted  to  geodetic  engineering,  it  has  no  special  application 
here,  but  is  inserted  only  to  establish  the  priority  of  the 
invention. 

Prof.  Viertel  first  used  the  telescope  of  an  eccentric  theod- 
olite for  conducting  surveys  in 
vertical  shafts,  by  suspending 
a  plummet  through  the  diop- 
ter ;  but  as  the  instrument  was 
not  steady  enough,  and  the  plum- 
met was  centered  only  with  great 
difficulty,  the  method  was  aban- 
doned as  impracticable. 

Prof.  A.  I^agel,  of  Dresden, 
had  a  nadir-instrument  (Fig.  19) 
constructed  without  vertical  axis, 
which  could  be  centered  over  a 
shaft  with  great  precision  by 
means  of  a  center-plug  in  the 
base,  which  was  afterwards  re- 
moved to  leave  the  opening  free 
for  the  purpose  designed.  The 
adjustment  of  his  instrument 
was  the  same  as  that  of  any  or- 
dinary theodolite.  To  obtain  a 
true  vertical  sight  he  first  set  a  plate  of  mercury  under  the  tel- 
escope somewhat  below  its  focal  distance.  Its  surface  must 
necessarily  be  a  perfect  horizon,  and  under  a  fair  illumination 
will  reflect  the  image  of  the  cross-hairs.  When  they  are 
brought  exactly  to  coincide  with  this  reflection,  the  optical  axis 
of  the  telescope  will  be  truly  vertical  if  it  is  originally  in  per- 
fect adjustment.  It  was  his  practice  to  revolve  the  telescope 
180°,  and  repeat  the  operation,  rectifying  any  defect  at  the 
bottom  of  the  shaft,  upon  a  mechanical  stage  which  was  pro- 


Nagel's  Nadir-Instrument. 


*  Die  Landmessung,  Dr.  C.  Bohm,  p.  605. 


22 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


FIG.  20. 


vided  with  co-ordinate  micrometer-scales  to  determine  the 
mean  projection.  The  experiments  of  both  Viertel  and  Nagel 
were  recorded  in  Der  Cwilingenieur  of  1878. 

In  1876  H.  D.  Hoskold  submitted  plans  to  Trough  ton  & 
Simms  for  a  similar  instrument;  but  the  plans  having  been 
lost  in  Paris,  its  introduction  in  England  was  allowed  to 
lapse.*  This  firm,  however,  in  1885.  devised  an  instrument 
(Fig.  20)  that  is  very  remarkable  among  the  instruments  of  its 

class.     Its  single  axis  of 

<j 

revolution  was  perfor- 
ated by  a  hole  f -inch  in 
diameter,  which  pro- 
vided a  sufficiently  large 
opening  without  the  ne- 
cessity of  increasing  the 
size  of  the  base,  so  as  to 
be  heavy  or  out  of  pro- 
portion. 

The  4J-inch  needle 
was  supported  at  the  top 
of  the  perforation  upon 
a  sort  of  little  flat  tri- 
dent, and  was  never  re- 
moved for  nadir  sight- 
ing. It  absorbed,  of 
course,  some  rays  of 
light,  but  did  not  inter- 
fere with  an  otherwise 
perfect  view.  The  bro- 
ken telescope,  which  was 
focused  by  movement 
of  the  ocular,  was  so  placed  that  its  prism  came  directly 
over  the  perforation,  and  vertical  sights  could  be  made  by 
setting  the  vertical  limb  to  the  zero  of  its  vernier,  which, 
in  turn,  was  insured  for  verticality  by  the  long  bubble  upon 
its  arm.  This  vernier  was  illuminated  by  the  reflection  of  a 
mirror,  so  placed  above  it  as  to  deflect  the  light  from  the 
large  lamp  opposite,  which  was  designed  to  counterbalance 


Troughton  &  Simms  Prismatic  Nadir  Dial. 


*  Trans.  Am.  Soc.  Civ.  R,  xxx.,  153,  1893. 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS.  23 

the  weight  of  the  telescope  and  vertical  circle.  The  outer 
circumference  of  the  compass-ring  was  graduated,  and  could 
be  read  to  minutes  by  opposite  vernier-plates  that  were  rigidly 
attached  to  the  compass-box.  The  circle  was  first  placed  at 
zero  and  held  by  the  pin,  with  looped  string,  shown  protrud- 
ing below,  and  the  telescope  moved  in  azimuth  by  means  of  the 
large  thumb-screw,  also  shown  below  the  compass-box. 

The  instrument  had  no  plummet.  In  ordinary  traversing 
the  instrument  was  set  up  at  any  convenient  position,  and  the 
station-point  sighted  in  afterwards  through  the  axis. 

Its  makers  volunteer  the  information  that  there  never  has 
been  much  of  a  demand  for  this  instrument,  and  that  it  is  now 
no  longer  made.  This  was,  perhaps,  because  of  the  inconveni- 
ence of  the  broken  telescope  in  general  work  and  the  condi- 
tions that  prevented  observations  in  dips  greater  than  45°  and 
less  than  90°. 

All  such  instruments  have  generally  been  allied  with  the 
straight-line  or  tunnel-transits.  In  1877  Buff  &  Berger  made 
such  an  instrument  for  GT.  H.  Crafts.  The  base,  having  the 
shape  of  a  horseshoe,  was  mounted  upon  three  leveling-screws. 
This  instrument  was  used  for  the  shaft-  and  tunnel-work  of  the 
Dorchester  Bay  sewer,  for  the  city  of  Boston,  and  afterwards 
to  re-establish  the  boundary  between  Massachusetts  and  E~ew 
York.* 

In  1887,  E.  A.  Geiseler,  now  Assistant  United  States 
Engineer  at  Savannah,  Ga.,  designed  plans  for  a  nadir-instru- 
ment in  which  both  the  graduated  circles  and  compass-box 
were  to  be  retained.  He  proposed  that  the  vertical  axis 
be  slightly  increased  in  diameter  and  perforated  with  a  hole 
-^-inch  in  diameter.  Its  upper  orifice  was  in  the  base  of  the 
compass-box  and  ordinarily  contained  a  plug,  so  designed  as  to 
support  the  needle.  When  vertical  sights  were  necessary,  the 
plug  with  needle  was  carefully  removed  and  set  just  to  one 
side,  by  means  of  a  lever-arm  operated  from  outside  the  com- 
pass-box. The  invention  received  editorial  comment  in  the 
Engineering  News  and  Railroad  Gazette,  at  the  time,  but  was  not 
executed  until  the  following  year,  when  the  F.  E.  Brandis 
Sons,  of  Brooklyn,  constructed  an  instrument  on  these  prin- 

*  Jour.  Ass.  Eng.  Societies,  vol.  iii.,  No.  9,  1884. 


24  THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 

ciples,  with  some  modifications  to  suit  the  ideas  of  their  cus- 
tomer. The  perforation  was  made  If  inches  in  diameter  and 
the  compass-box  was  dispensed  with  entirely.  In  its  place  was 
supplied  a  trough-box  compass  suspended  from  the  horizontal 
axis  in  a  manner  similar  to  that  described  in  the  works  of  Prof. 
"Weisbach.*  The  plummet  was  suspended  from  a  hinged  plate 
below,  which,  when  released,  permitted  a  clear  vertical  sight 
with  the  main  telescope.  The  length  of  the  vertical  axis  was 
reduced,  owing  to  its  large  diameter ;  but  this  did  not  make  a 
well-proportioned  lower  base,  and  the  instrument  never  was 
duplicated. 

Fenwick,  of  Durham,  was  the  first  to  introduce  in  England 
(in  1804)  a  general  system  of  mine-surveying  by  observing  only 
the  magnetic  bearing  of  the  first  course.  He  points  out  in  his 
work  that  as  mines  are  now  becoming  more  skillfully  and  eco- 
nomically developed,  a  more  scientific  system  of  engineering  is 
essential.  "  The  general  use  of  the  magnetic  needle,"  he  says, 
"  in  subterraneous  surveys^  has  been  found  to  be  a  great  source 
of  error  on  account  of  ferruginous  substances,  which  exist  in  all 
mines,  attracting  the  needle;  whence,  in  general,  old  surveys 
and  plans  are  found  to  be  extremely  defective."  For  these 
reasons  he  suggests  that,  except  in  beginning  the  survey,  the 
use  of  the  needle  be  abandoned,  and  declares  it  much  to  be 
regretted  that  the  general  use  of  the  compass  still  prevailed  and 
mapping  was  conducted  on  the  original  diagrams  through  scores 
of  years  without  any  consideration  for  secular  variation.  He 
further  says  :  "  If  the  student  be  acquainted  with  the  applica- 
tion of  spherical  trigonometry  to  astronomy,  he  will  find  the 
following  method  of  finding  the  true  meridian  to  be  greatly 
preferable  .  .  .  ."  But  herein  lies  the  secret  of  the  survival  of 
the  compass,  which  could  always  be  relied  upon  as  indicating 
a  relative  direction.  What  did  most  of  such  men  as  were  en- 
gaged in  digging  ore  from  the  earth  know  or  care  about  the 
sciences,  or  how  to  consult  and  interpret  the  Ephemeris  ? 

It  was  lack  of  education  and  a  want  of  the  means  for  the  dif- 
fusion of  knowledge,  as  exemplified  in  our  colleges  and  insti- 
tutes of  to-day,  that  made  these  primitive,  simple  and  unreliable 
methods  so  enduring.  Fenwick  no  doubt  found  his  adherents ; 

*  Die  Neue  Markscheidekunst,  J.  Weisbach,  Braunschweig,  1859. 


THE    EVOLUTION  OF    MINE-SUKVEYING    INSTRUMENTS. 


25 


FIG.  21. 


but  in  the  early  part  of  this  century  dialing  with  the  needle 
alone  predominated  in  England,  as  well  as  in  America,  where 
such  engineering  as  was  necessary  was  performed  with  some 
foreign  type  of  dial  or  hanging-compass. 

In  recent  years  the  hanging-compass  has  been  re-designed 
by  Queen  &  Co.,  of  Philadelphia,  and  is  said  to  be  still  indis- 
pensable to  certain  surveyors  in  Virginia  and  Pennsylvania.* 
The  excuse  for  employing  the  hanging-compass  in  cramped  and 
tortuous  channels  to-day,  however,  seems  absurd;  for  the 
transit  can  be  made  to  do  the  most 
reliable  work,  even  when  removed 
from  the  tripod,  anywhere  a  man 
can  take  it. 

The  earliest  American  instruments 
were  descendants,  as  it  were,  like  the 
American  people,  of  English  ances- 
try, with  an  infusion  of  German  and 
French  influences,  which  have  ever 
since  combined  with  natural  Ameri- 
can skill  to  make  them  the  resultant 
of  the  most  approved  appliances  and 
methods. 

William  J.  Young,  established  in 
Philadelphia  in  1820,  introduced  the 
first  American  type  of  transit  in 
1831,  probably  after  that  of  Rams- 
den  (1 803),  who  introduced  the  tran- 
sit principle  in  small  English  the- 
odolites at  that  time.  The  earliest  American  engineers  objected 
to  the  intricacies  of  the  ordinary  English  theodolite  for  reasons 
already  stated ;  but  "  most  of  these,"  says  Mr.  Young,  "  who 
had  only  local  training,  could  not  understand  the  superiority 
of  vernier-circles  over  the  compass-sights  for  seeing  past  or 
around  a  tree  or  other  obstruction !" 

Young's  first  transit  was  graduated  to  read  by  vernier  in- 
side the  compass-box  to  3';  the  needle  was  5  inches  long,  and 
the  telescope  9  inches  long  and  of  low  power. 

The  first  distinctive  mine-transit  that  ever  appeared  in  Amer- 


Draper's  Mine -Transit. 


En.g.  and  Min.  Jour.,  vol.  Hi.,  p.  125,  Aug.  1,  1891. 


26 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


ica  was  introduced  by  Edmund  Draper  (established  in  Phila- 
delphia, 1815),  about  the  year  1850.  Fig.  21  is  reproduced 
from  a  photograph  kindly  loaned  by  F.  C.  Knight,  his  successor, 
who  says: 

"It  had  full  vertical  and  horizontal  circles,  each  of  which  was  read  to  minutes 
by  one  vernier.    The  upper  horizontal  plate  was  extended  somewhat  beyond  the 

FIG.  22. 


.     Borchers'  Eccentric  Instrument,  in  an  Inclined  Shaft.     Instrument  and 
Lamps  Supported  on  "Freiberg  Brackets." 

compass-box,  ending  in  two  piers  that  supported  the  pillars  of  the  telescope.  The 
open  space  between  them  permitted  true  vertical  sights  or  the  observation  of  any 
angle  between  the  horizon  and  nadir,  without  any  correction  for  eccentricity  be- 
yond the  mere  mechanical  addition  of  the  telescope's  distance  from  the  instrument's 
center  to  the  base  component.  The  telescope's  power  was  16  diameters." 

Considering  the  times,  the  design  of  this  pioneer  instrument 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS.  27 

is  both  original  and  praiseworthy,  and  in  some  respects  is  supe- 
rior to  the  eccentric  model  of  Prof.  E.  Borchers  (Fig.  22),  which 
he  introduced  in  1835  for  special  surveys  in  inclined  shafts. 
Zenith  instruments  in  Germany  had  for  some  time  previously 
been  constructed  with  eccentric  telescopes,  but  had  never  before 
this  date  been  used  in  mines.  In  his  work  on  mine-surveying* 
Borchers  says  that  while  the  ordinary  theodolite  (since  1832) 
has  been  employed  for  most  mine-work,  this  instrument  is  most 
convenient  for  inclined  shafts,  though  not  intended  for  magnetic 
observations. 

The  first  instrument  of  this  kind  was  made  for  him  by  Breit- 
haupt.  Both  circles  were  16  cm.  in  diameter  and  graduated  to 
read  20".  The  hub  of  the  telescope  was  rigidly  attached  to  a 
flattened  extension  of  the  horizontal  axis  by  four  screws,  and 
the  optical  axis  was  made  to  be  exactly  at  right  angles  to  the 
axis  of  revolution  by  lateral  movement  of  the  small  cylinder 
that  contained  the  eye-piece  and  diaphragm.  The  intersection 
of  the  cross-hairs  was  then  made  to  coincide  with  the  optical 
axis  thus  established,  independently,  by  the  usual  methods. 

He  used  an  artificial  horizon  in  taking  steep  upward  sights  to 
an  84°  limit,  and  recommends  it  as  being  convenient  and  port- 
able, but  his  enthusiasm  never  became  contagious.  Observa- 
tions were  made  first  on  one  side,  then  on  the  other ;  a  mean 
was  deduced,  and  the  true  inclination  was  calculated,  without 
any  correction  for  eccentricity,  which  in  the  longest  courses 
amounts  to  only  two  or  three  seconds.  One  of  the  most  inter- 
esting features  about  this  instrument  is  the  mountings,  known 
since  the  improvement  of  Prof.  Dr.  Schmidt,  in  1882,  as  the 
"  Freiberg  brackets,"  upon  which  the  instrument  and  signal- 
lamps  rest  without  being  clamped.  They  have  taken  the  place 
of  the  tripod  to  a  considerable  extent  in  Germany,  for,  without 
much  effort,  they  can  be  screwed  into  the  timbering  and  per- 
form duty  in  low  places  where  tripods  could  not  be  set  up. 
The  stand  had  been  made  of  wood  until  1885,  when  wood  was 
exchanged  for  metal  that  would  not  wear. 

In  that  year  Prof.  Chrismar,  of  the  Schemnitz  School  of  Mines, 
introduced  a  support  consisting  of  two  hollow  wrought-iron 
pipes,  with  steel  teeth  at  the  outer  ends,  and  sliding  one  within 

*  Die  Praktische  Markscheidekunst,  E.  Borchers,  Hanover,  1870,  p.  131. 


28 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 


FIG.  23. 


the  other,  in  such  a  way  that  they  could  be  firmly  clamped 
between  drift-timbers  at  distances  varying  from  three  to  seven 
feet,  and  not  interfere  with  the  passage  of  tram-cars  or  trucks. 
The  theodolite-stand  was  then  clamped  to  the  center,  making 
a  combined  weight  of  sixteen  pounds. 

This  was  similar  to  the   support  of  Kawerau  (1862),  whose 

staves  slid  vertically 
side  by  side,  being 
clamped  by  girders. 
To  this  the  bracket 
was  attached,  and  ar- 
ranged to  move  by 
jointed  arms  in  three 
directions  to  facilitate 
centering. 

In  1845  Prof.  C. 
Combes,  of  the  Paris 
School  of  Mines,  in- 
troduced in  France  a 
modification  of  the 
eccentric  theodolite  which 
has  been  in  general  use  there 
ever  since,  until  in  late  years 
it  is  being  replaced  by  the 
concentric  telescope ;  for 
however  well  this  or  any 
other  such  instrument  may 
be  constructed,  the  number 
of  parts  and  the  eccentricity 
of  the  telescope,  which  must 
be  counterbalanced  by  a 
weight,  are  permanent  causes 
of  derangement.  Fig.  23  shows  a  16  cm.  circle,  modernized 
pattern,  built  by  H.  Morin,  of  Paris ;  but "  the  original,"  says  M. 
Andre  Pelletan,  ""had  no  compass,  but  a  large  horizontal  circle 
graduated  to  read  30",  surmounted  by  a  delicate  striding  level, 
as  in  Borchers'  theodolite."  This  style  of  mounting  the  tele- 
scope prostrate  upon  the  vertical  circle  was  first  practised  by 
Prof.  Morin,  of  Paris,  in  1634,  when  he  attached  a  telescope  to 
the  movable  index  of  a  graduated  arc  for  the  purpose  of  meas- 
uring the  diameter  of  fixed  stars. 


Combes'  s  Theodolite,  with  Eccentric  Signal  Targets. 


FIG.  23A. 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS.  29 

It  is  customary  in  Germany,  France  and  other  foreign 
countries  to  use  with  the  eccentric  theodolite  a  twin  target, 
which  operates  interchangeably  with  the  instrument.  It  is 
called  Doppdsiynal  by  the  Germans  and  viseur  de  mine  by  the 
French,  and  is  so  constructed  that  each  target  is  as  far  re- 
moved from  the  center  of  the  signal  as  the  telescope  is  from 
the  center  of  the.  instrument.  This  provides  against  any  neces- 
sity for  correction  in  reading  horizontal  angles,  whether  the 
telescope  is  used  on  one  side  or  the  other,  normally  or  reversed. 
In  setting  it  up,  upon  its  own  tripod,  the  assistant,  after  level- 
ing it  by  means  of  the  box-bubble  between  the  standards,  directs 
the  sighting-tube  at  a  light  held  at  the  instrument. 

Combes's  instrument,  as  well  as  all  others  in  France,  at  the 
option  of  the  engineer,  is  graduated  by  the  sexagesimal  system 
common  in  America  and  most  European  countries,  or  by  the 
centesimal  system,  in  which  each  quadrant  contains  100  grades 
(as  adopted  in  1801  at  the  suggestion  of  Laplace  when  the 
metric  system  of  weights  and  measures  was  proclaimed  legal 
and  compulsory). 

The  division  of  the  circle  into  400  degrees  for  compasses  and 
mine  theodolites  is  still  of  doubtful  benefit,  as  the  minute  spaces 
are  made  to  correspond  to  only  32.4  sexagesimal  seconds,  while 
the  centesimal  seconds  are  so  diminutive  as  to  be  practically 
impossible  in  small  circles. 

A  want  of  uniformity  in  denominate  nomenclature  also  tends 
to  retard  its  progress.  The  logarithmic  tables  of  Borda  (1801), 
Plauzolis  (1809),  Gauss  (1873),  and  Gravelius  (1891),  are  all 
at  variance  in  this  respect ;  but  the  proposal  of  Prof.  S.  Jordan 
in  1891  to  write,  for  instance,  24g  86C  50CC,  seems  to  deserve 
general  adoption. 

In  America  the  decimal  system  of  graduation  was  introduced 
by  S.  "W".  Mifflin,  C.E.,  for  construction-work  on  the  Pennsyl- 
vania Railroad,  after  the  methods  of  M.  Minot,  engineer  for  the 
Orleans  Railroad,  who  in  1856  popularized  in  France  that 
system  of  railroad  engineering  known  as  tacheometry. 

For  about  thirty  years,  Young  has  made  transits  in  which 
one  vernier  reads  the  sexagesimal  circle  in  sixtieths,  etc.,  and 
the  opposite  one  in  tenths  and  hundreds ;  but  except,  perhaps, 
for  railroad  work,  in  which  the  tangential  deflection  of  curves 
can  be  laid  out  with  facility,  the  French  system  of  graduation 


30  THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

has  never  met  in  America  the  favor  accorded  to  the  metric  sys- 
tem of  weights  and  measures. 

While  considering  the  eccentric  type  of  mine-theodolite, 
it  may  be  well  to  notice  here,  though  not  in  exact  chronological 
order,  its  introduction  and  application  in  England. 

In  1869  Louis  Casella,  of  London,  introduced  a  small  portable 
FlG  24  instrument  for  Alpine  and  mili- 

tary surveying  (Fig.  24),  by  which 
good  results  have  been  obtained, 
not  only  in  the  determination  of 
astronomical  time  and  latitude, 
but  in  shaft-work  in  the  British 
mines. 

Its  circles  are  only  3-inch,  grad- 
uated to  read  minutes,  the  vertical 
circle  being  placed  opposite  the 
telescope,  to  aid  somewhat  in 
g-  making  the  equipoise  perfect.  It 
is  mounted  upon  the  tribrach  lock- 
ing-plate, introduced  by  Everest 

Casella's  Portable  Theodolite.  °. r,  .    '  ,   ...       .      1OOJ_ 

with,  his  theodolite  in  1837,  and 

since  possessed  of  greater  popularity  than  his  instrument.  This 
miniature  theodolite,  weighing  only  3  J  pounds,  with  the  pocket 
mine-theodolite  of  Breithaupt  (1869)  with  8  cm.  circle,  having 
a  total  weight  of  1.7  kg.,  and  the  aluminum  mine-transit  of 
Keuffel  &  Esser,  weighing  only  2.1  kg.,  are  about  the  smallest 
instruments  we  have  to  deal  with.  The  only  strong  argument 
in  their  favor  is  their  portability,  but  efficiency  ought  not  to  be 
sacrificed  in  this  way  for  a  novelty. 

J.  Winspear,  of  Hull,  in  1870,  made  an  eccentric  instrument 
for  Hoskold,  to  which  was  given  the  distinctive  name  of  Angleo- 
meter.  It  differed  from  Casella's  model  in  that  the  compass-box 
was  raised  somewhat  above  the  horizontal  plates  so  that  the 
axis,  connecting  the  telescope  on  one  side  with  the  vertical 
circle  on  the  other,  should  pass  between.  The  long  axial  bub- 
ble being  then  placed  on  the  side  nearest  the  vertical  circle, 
the  compass  was  left  perfectly  unobstructed,  as  we  find  it  in 
Prof.  Combes's  model.  Combes's  theodolite  was  the  lowest 
form,  because,  in  placing  both  telescope  and  vertical  circle  on 
one  side,  it  had  no  need  of  a  horizontal  axis. 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS.  31 

The  Angleometer  received  an  award  at  the  London  Exhibition 
of  1872,  where  there  was  also  displayed  with  it  a  plain  compass- 
dial,  with  plain  sights  on  one  side  and  semicircle  opposite. 

The  use  of  the  eccentric  telescope  has  by  no  means  become 
general  in  mine-surveying  in  England,  but  important  and  very 
satisfactory  work  has  been  conducted  with  it.  Horizontal 
angles  are  usually  repeated,  first  on  one  side,  then  on  the  other, 
to  obtain  a  mean  reading;  but  if  only  on  one  side,  in  platting, 
a  small  circle  is  drawn  to  scale  about  the  station  equal  in  radius 
to  the  eccentricity  of  the  telescope,  and  the  courses  laid  out 
tangentially  to  this  by  use  of  the  English  system  of  platting 
with  the  parallel  ruler. 

Within  the  present  century  greater  improvements  in  mine- 
surveying  methods  and  the  instruments  used  in  conducting 
them  have  been  achieved  than  in 
all  the  previous  history  of  the 
world ;  but  by  far  the  greater 
share  of  this  century's  progress 
has  occurred  during  the  past  fifty 
years.  A  hundred  years  ago  an 
engineer  could  err  occasionally 
with  good  and  sufficient  reason. 
To-day  there  is  absolutely  no  ex- 
cuse for  anything  but  perfect 
results. 

America  and  Germany  have 
been  perhaps  more  largely  in- 
strumental in  perfecting  the  ap- 
paratus used  in  mine-surveying  in  this  period  than  England, 
though  the  latter  is  entitled  to  a  just  share  of  credit  in  an 
endeavor  to  perfect  the  construction  of  the  dial  or  circumfer- 
enter,  so  as  to  obviate  the  necessity  of  using  the  more  expen- 
sive theodolite. 

In  1850  John  Hedley,  H.  M.  Inspector  of  Mines,  being  con- 
vinced of  the  inconvenience  of  the  vertical  arc  on  Lean's  dial 
in  obstructing  frequently  a  clear  reading  of  the  needle,  caused 
John  Davis,  of  Derby,  to  construct  an  improved  model  (Fig.  25). 
Its  principal  feature  was  the  swinging  limb,  by  which  vertical 
sights  up  to  about  50°  could  be  observed  and  read  upon  the 
index  of  the  vertical  arc  at  the  side,  leaving  the  face  of  the 


32  THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

compass  quite  unobstructed.  With  the  Hedley  dial,  the  miners' 
chain  of  10  fathoms  or  120  links  still  continued  to  be  the 
means  of  linear  measurement,  and  gave  the  early  surveyor 
nearly  as  much  trouble  in  attempting  to  correct  for  its  cumu- 
lative and  compensating  errors  as  for  the  vagaries  of  his  needle. 
It  was  (and  is  still)  made  with  the  ten  end-links  of  brass,*  and 
when  used  for  measuring  is  laid  on  the  floor  and  each  chain- 
length  marked  with  a  piece  of  chalk,  the  entire  course  being 
represented  by  so  many  fathoms,  feet  and  inches. 

In  chaining  up  slopes  the  plumb-line  was  still  used,  as  on  the 
surface.  This  is  the  very  earliest  method  of  conducting  meas- 
urements on  inclined  planes,  and  gave  rise  to  the  practice,  yet 
widely  followed  in  Europe,  of  conducting  surveys  in  inclined 
shafts  by  successive  plumbing  and  leveling.  The  several  lengths 
of  the  plumb-line  are  recorded  as  the  vertical  components,  and 
the  several  distances  from  the  base  of  one  plumb  to  the  point 
of  suspension  of  the  next  make  up  the  horizontal  aggregate. 

In  France  and  Germany  special  appliances  have  been  made 
to  perform  this  work.  That  of  Mr.  0.  Cseti,  of  Hungary,  is 
no  doubt  the  most  recent. f  Briefly,  it  is  a  small  leveling  tele- 
scope fastened  by  a  sliding  and  clamping  collar  to  a  hollow 
square  rod  of  0.67-inch  section  and  5  feet  long,  that  may  be 
suspended  from  any  station.  From  the  top  downward  the  rod 
is  graduated  to  cm.,  while  the  vernier  on  the  sliding  collar  de- 
termines vertical  distances  with  great  precision.  Lengthening- 
bars  are  also  supplied.  Its  total  weight  is  5  kg. 

While  speaking  of  the  English  chain,  it  must  be  noted  here 
that  the  chain  of  Eittenhouse,  which  comprised  80  links  or  66 
feet,  was  quite  generally  used  in  American  mines  until  Eckley 
B.  Coxe  and  others  started  a  reformation,  some  twenty-five 
years  ago,  in  favor  of  the  steel  band  that  has  now  practically 
consigned  the  chain  to  President  Cleveland's  "  innocuous 
desuetude."  In  1874  Dr.  R.  W.  Raymond  said:  "While  so 
much  improvement  in  recent  years  has  been  made  in  mine-in- 
struments, the  chain  remains  unaltered.  Nothing  can  be  in- 
herently more  objectionable,  as  a  standard  of  measurement, 
than  a  chain  composed  of  links  that  wear  by  friction,";);  and, 
we  may  add,  connecting-rings  that  elongate  by  tension. 

*  Colliery  Management,  J.  Hyslop,  Wishaw,  1870,  p.  23. 

f  Berg- und Huttenm.  ZeUung,  vol.  liv.,  p.  391,  Nov.  8, 1895.    J  Trans.,  ii.,  224. 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 


33 


FIG.  26. 


In  the  first  American  steel  tapes  the  points  of  graduation 
were  marked  by  impressed  figures  on 
white  solder,  or  by  small  brass  rivets ; 
but  etched  graduations  and  figures  now 
predominate.  The  500-foot  tape  used 
by  the  writer  is  one  made  by  Keuffel 
&  Esser,  of  ISTew  York,  and  exhibited 
by  them  at  the  World's  Fair.  It  is  T\ 
of  an  inch  wide,  graduated  at  every 
foot  throughout  its  entire  length,  and 
wound  on  a  gun-metal  reel,  the  conve- 
nience of  which  will  appear  obvious  by 
inspection  of  the  illustration,  Fig.  26. 

With  the  Hedley  dial  went  the  con- 
tinuance of  the  practice  of  connecting 
the  surface-  and  underground-surveys 
by  magnetic  observations,  which  opera- 
tion was  greatly  facilitated  by  its  rocking  limb.  In  1856,  how- 
ever, Arthur  Beanlands,  C.E.,  under- 
took a  purely  astronomical  method  of 
accomplishing  this  result  by  use  of  the 
theodolite  alone;  but  the  observation 
of  stars  from  the  bottom  of  a  vertical 
shaft  was  attended  with  such  diificulty 
that  he  projected  an  alignment,  first 
from  above,  then  from  below,  by  the  use 
of  lights,  with  excellent  results.* 

Thirteen  years  before,  Thomas  Baker, 
C.E.,  had  suggested  and  used  a  method 
(held  in  derision  by  colliery-surveyors  at 
that  time)  of  suspending  from  a  straight- 
edge two  fine  copper  wires  by  heavy 
weights  in  mercury,  and  completing  the 
survey  with  the  theodolite  and  inter- 
changeable tripods  and  targets,  f 

The  accuracy  of  this  method,  has  al- 
ways been  somewhat  impaired  by  the 
extremely  short  base  from  which  to  work,  and  the  inevitable 


Skeleton  Reel  for  Long 
Mine-Tapes. 


FIG.  27. 


Schmidt's  Centering 
Apparatus. 


*  Trans.  North  Eng.  Inst.  M.  E.,  vol.  iv.,  p.  267. 

f  Subterraneous  Surveying,  Fenwick  and  Baker,  1888,  p.  40. 


34 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


FIG.  28. 


oscillation  in  the  wire ;  but  the  centering-apparatus  of  Prof.  Dr. 
Schmidt  (1884),  Fig.  27,  has  regulated  the  method  to  a  nicety. 
The  vibrations  are  carefully  measured  by  repeated  observation 
on  co-ordinate  scales,  and  the  wires  are  finally  clamped  in  exact 
mean  position.  The  instrument  is  then  ranged  into  their  align- 
ment, and  presents  a  means  only  less  accurate  than  the  later 
method  of  suspending  one  wire  in  each  of  two  vertical  shafts, 
thus  securing  a  length  of  base  limited  only  by  the  distance 
between  the  shafts.* 

In  England,  Beanlands  is  usually  credited  with  having  first 
used  the  theodolite  to  connect  the  underground  and  surface- 
surveys;  but  Bourne's  method  of  1843  and  Borchers'  of  1835 

certainly  are  entitled  to  precedence. 
In  fact,  we  may  nearly  always  look 
to  Germany  for  the  beginning  of  all 
important  steps  in  the  advancement 
of  mining  engineering. 

The  eccentric  telescope  of  Borchers 
was  found  so  convenient  for  the  pur- 
poses intended  that  it  was  employed 
by  American  engineers  as  a  side-aux- 
iliary, which  could  be  attached  to 
concentric  instruments  at  will,  and 
removed  when  not  in  use.  The  first 
American  types  were  of  simple  con- 
struction. The  horizontal  axis  of  the 
main  telescope  was  perforated  with 
a  hole  large  enough  to  permit  a  spindle,  conjugate  with  the  hub 
of  the  auxiliary,  to  be  inserted  and  held  fast  by  pins  (see  Fig. 
28),  such  as  are  used  in  the  Y's  of  a  level. 

Adams,  in  his  Geometrical  and  Graphical  Essays  of  1791, 
says :  "In  the  present  state  of  science  it  may  be  laid  down  as 
a  maxim  that  every  instrument  should  be  so  contrived  that  the 
observer  may  examine  and  rectify  the  principal  parts ;  for  how- 
ever careful  the  maker  may  be,  it  is  not  possible  that  any  in- 
strument should  long  remain  accurately  fixed  as  it  came  from 
the  manufacturer."  But  we  find  in  these  first  forms  (see,  for 
instance,  Fig.  29)  no  means  of  testing  the  adjustment  of  the 
side-auxiliary;  and  the  startling  fact  must  be  recorded  that, 

*  Methoden  der  Unterirdischen  Orientirung,  M.  Schmidt,  Berlin,  1892. 


Early  American  Method  of 
Mounting  Side-Auxiliary. 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 


35 


FIG.  29. 


almost  up  to  the  present  time,  the  adjustment  of  all  auxiliary 
telescopes  has  had  to  he  assumed  as  correct  upon  the  guarantee 
of  the  maker,  at  the  risk  of  their  work- 
ing loose  on  their  bearings. 

When  side-auxiliary  telescopes  first 
came  into  use  in  America,  new  instru- 
ments  were   always    equipped   in   the 
manner  just  described  ;  but  when  engi-   / — 
neers  who  had  been  using  simple  con-  v — 
centric  instruments  caught  the  conta- 
gion, they  sent  their  transits  to  the  fac- 
tory to  receive  this  valuable  adjunct. 
In  such   cases   it  was  customary  with 
the  house  of  Young  to  mount  the  side- 
telescope    upon    the   vertical    circle   by    Keuffel  &  Esser's  Concentric 
means    of    set-screws    and    clamping-      Instrument,  with  Side-Aux- 
plates,  in  the   manner  shown  in,  Fig. 
30.     In  the  event  that  the  instrument  had  not  been  provided 

FIG.  30. 


Side-Auxiliary  Mounted  on  Vertical  Circle. 

originally  with  a  full  vertical  circle,  one  was  permanently  at- 
tached to  an  improvised  prolongation  of  the  horizontal  axis. 

4 


36 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


FIG.  31. 


The  adjustment  of  such  an  appliance  was  no  easier  that  when 
it  was  mounted  on  a  spindle,  but  the  method  presented  the 
advantage  of  holding  the  auxiliary  more  firmly  in  the  position 
in  which  it  was  placed. 

The  shifting  tripod-head,  shown  in  Fig.  30,  was  made  hy 
Young  in  1858,  and  has  been  ever  since  a  most  valuable  con- 
venience to  mining  engineers. 

As  the  German  method  of  mounting  eccentric  telescopes  had 

its  influence  upon  the  early 
manufacture  of  American  side- 
auxiliaries,  so  also  we  may 
notice  the  effect  of  the  French 
types  in  the  model  (now  obso- 
lete) presented  in  Fig.  31, 
which  was  known  as  the 
"  Lake  Superior  "  pattern, 
and  used  in  1858,  when  the 
copper-mines  of  that  region 
first  became  valuable. 

The  upper  plates  were  not 
unlike  those  of  an  ordinary 
transit. 

The  smaller  upper  telescope 
was  intended  only  for  general 
work,  and  provided  simply 
with  a  short  60° -arc  and 
loose  vernier -arm,  as  first 
made  by  Young  in  1850. 

This  style  of  vernier  may  be 
clamped  in  any  position,  and  by  repetition  made  to  read  any 
angle  up  to  90°.  The  vertical  plate  was  similar  in  shape  to  the 
horizontal,  to  which  it  was  attached.  It  was  always  at  hand 
for  vertical  observations,  but  its  additional  weight,  its  exposed 
position  and  delicate  construction,  conspired  to  insure  the  re- 
jection of  this  instrument  in  favor  of  the  regular  concentric 
types. 

In  the  meantime,  some  progress  had  been  made  in  Germany 
with  a  view  to  supplement,  at  least,  the  hanging-compass  with 
such  instruments  as  could  be  made  to  verify  it,  and  even  to 


Lake  Superior  Pattern. 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


37 


FIG.  32. 


supplant  it.     In  1861  Prof.  Junge,  of  Freiberg,  invented  his 
Goniometer*  (Fig.  32). 

The  inventor  apologetically  announces :  "  This  instrument 
will  be  found  a  great  convenience  for  use  with  compasses  in 
mines,  if,  however,  it  shall  not  furnish  some  means  of  attrac- 
tion;" but  being  himself  convinced  of  its  superiority,  he  re- 
counts among  its  advantages :  First.  All  that  can  be  accom- 
plished by  use  of  a  compass  can  be  determined  by  the 
goniometer.  Second.  It  can  be  used  anywhere  in  the  mine, 
and  even  to  great  advantage  in  in- 
clined shafts,  if  the  conditions  are  not 
too  cramped.  Third.  The  accuracy 
in  reading  angles  is  more  pronounced, 
and  gross  errors  cannot  be  com- 
mitted, etc. 

The  horizontal  circle  was  small,  as 
compared  with  the  height  of  the 
standards,  and  graduated  to  read 
minutes  of  arc.  The  instrument  had 
no  vertical  circle,  as  the  old  method 
of  cords  and  suspended  clinometer 
was  adhered  to,  with  the  early  mode 
of  setting  up  instruments  of  this  class. 
A  plank  was  wedged  between  the 
walls,  and  a  hole  bored  in  which  to 
set  and  clamp  the  spindle  of  the 
instrument,  as  illustrated  more  fully 
in  Fig.  33.  This  system  was  first 
used  and  taught  by  Prof.  Lang  von 
Hanstadt,  of  the  Schemnitz  Bergakademie  in  Austria,  as  early 
as  1835, f  and  was  subsequently  recommended  by  Prof.  Weis- 
bach  in  1859.  In  this  modern  system  here  portrayed,  the 
instrument  and  targets  are  of  equal  height,  and  are  made  in- 
terchangeable in  the  3-legged  base  by  opening  the  set-screw 
at  the  side.  In  this  way  the  target  may  be  removed,  the  coni- 
cal spindle  of  the  instrument  set  into  the  socket,  and  the 
tangent-screw  of  the  azimuth-axis  fitted  to  work  upon  the 
pin  shown  protruding  from  the  right  leg.  This  system  of  set- 


Junge's  Goniometer. 


*  Die  Geometrischen  Instrument^  C.  G.  K.  Hunaus,  Hannover,  1864. 
f  Anleitung  zur  Markscheidekunst,  J.  N.  L.  von  Hanstadt,  Pesth,  1835. 


38  THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

ting-up  is  not  sb  complicated,  delicate  or  expensive  as  the 
Freiberg  brackets,  but  takes  a  little  more  time  to  secure,  and 
cannot  be  used  in  large  openings,  any  more  than  the  other  can 
be  used  in  rock-tunnels  where  there  is  no  timbering. 

The  telescope  of  Junge's  goniometer  revolved  completely  in 
its  standards,  and  could  be  made  to  sight  objects  downward  in 
declivities  unusual  with  most  theodolites.  If  steep  upward 
sights  were  necessary,  the  eye-piece  prism  was  used  arid 
attached  to  the  ocular  by  means  of  a  spring-clamp.  The  tele- 

FIG.  33. 


Breithaupt's  Modern  Mine-Theodolite  with  interchangeable  Targets  and 
the  Spreitzen  system  of  setting-up. 

scope  was  provided  with  two  diopters  for  ranging  it  into  line, 
though  for  universal  observation  these  preceded  the  telescope 
and  must  be  looked  upon  as  the  forerunners  of  extended  sights. 
The  origin  of  sightrvanes  must  be  sought  in  the  very  earliest 
fimes,  and,  as  applied  to  mine-surveying,  in  the  first  instruments 
ever  used.  When  they  had  outgrown  their  usefulness  as  prin- 
cipal factors,  they  were  used  in  conjunction  with  the  telescope, 
first  to  assist  in  directing  it  upon  an  object,  and  later,  being 
lengthened  and  provided  with  windows,  to  make  observations 
in  dips  that  approached  vertically.  When  and  by  whom  they 
were  first  used  for  this  purpose  the  writer  is  now  unable  to 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 


39 


say ;  but  the  instrument  shown  in  Fig.  34  was  built  by  Young 
at  an  early  date  and  shipped  to  Mexico.  The  tripod  upon 
which  it  was  mounted  was  one  of  America's  first  adjustable-leg 
forms,  and  was  very  heavy  and  awkward. 

Diopters  and  extended  sights  had  been  used  for  observing 
very  near  objects  that  came  within  the  focus  of  old-time  tele- 
scopes ;  but  their  later  application  for  vertical  sighting  gave 
rise  in  America,  no  doubt,  to  the  top-auxiliary  telescope. 

The  available  evidence  concerning  the  invention  and  intro- 


FIG.  34. 


FIG.  35. 


Draper's  Top- Auxiliary. 


Instrument  with  Sight-Vanes. 


duction  of  the  top-auxiliary  telescope  is  not  conclusive,  but 
Knight  says  that  Draper  was  probably  the  first  to  introduce  it 
in  1840.  The  instrument  shown  in  Fig.  35  is  easily  identified  as 
Draper's  by  the  peculiar  style  of  tripod-head.  The  base-plate 
of  the  instrument  is  set  upon  two  threaded  spindles  project- 
ing from  the  tripod-head,  and  held  in  position  by  two  milled 
nuts. 

Gurley's  first  top-telescopes  (Fig.  36)  were  attached  to  the 
main  by  coupling-nuts  and  "  steady-pins  "  which  provided  for 
their  ready  removal  and  replacement.  Until  very  recent  years 


40 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 


these  have  been  made  by  all  American  makers  in  styles  similar  to 
the  first  model,  with  no  means  of  effecting  adjustment  for  par- 
allelism and  alignment  beyond  the  guarantee  of  the  maker, 
which,  in  the  best  makes,  could  not  be  relied  upon  as  perma- 
nent. 

So  far  as  the  writer  knows,  no  very  serious  errors  of  execu- 
tion have  been  recorded  during  the  fifty  years'  use  of  the  non- 
adjustable  auxiliary,  though  there  has  always  been  room  for 
such  error  in  the  fact  that  it  was  hardly  possible  to  place  the  in- 
strument a  second  time  in  the  exact  position  it  had  once  occu- 
pied. 

The  growing  sentiment  among  American  engineers  in  favor 
of  instrumental  construction  permitting  accurate  adjustment  led 

FIG.  36. 


Gurley's  Top-Telescope. 


A  German  Improvement. 


Per  Larsson,  E.M.,  then  at  Vulcan,  Mich.,  to  begin  in  1882  a 
reconstruction  of  the  top-telescope  by  providing  at  least  that  it 
should  be  capable  of  most  of  the  adjustments  of  a  level,  by 
placing  it  in  Y's  that  were  permanently  fixed  to  the  main 
telescope.  Such  an  instrument  was  made  for  him  by  Buff  & 
Berger,  of  Boston,  and  was  then  justly  considered  very  com- 
plete, inasmuch  as  the  line  of  collimation  of  the  top-telescope 
could  be  adjusted  independently  by  rotation  in  its  Y's.  The 
adjustment  for  parallelism,  however,  was  too  complex  an  ope- 
ration to  be  undertaken  outside  the  factory. 

In  the  later  models  the  Y's  were  put  on  top,  so  as  to  be 
partly  balanced  by  the  long  bubble  beneath ;  but  in  Mr.  Lars- 
son's  instrument  they  were  put  under  the  telescope,  so  as  to  be 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 


41 


FIG.  37. 


out  of  harm's  way,  and  worked  very  satisfactorily.  The  later 
model  shown  in  Fig.  37  is  provided  with  the  gradientor-screw, 
as  applied  by  Prof.  Stampfer,  of  Vienna,  in  1873,  to  the  tan- 
gent movement  of  the  horizontal  axis  of  transit-instruments. 
As  employed  in  the  rapid  determination  of  distances  it  was 
first  used  by  him  in  1839,  and  mentioned  in  his  work  of  that 
year.* 

The  silvered  head,  appearing  in  Figs.  37  and  38,  is  gradu- 
ated into  50  parts,  and  the  screw  is  cut  with  such  a  value  as  to 
cause  the  horizontal  web  of  the  tele- 
scope to  move,  for  each  graduation 
of  the  head,  over  a  space  of  .01  foot 
upon  a  rod  100  feet  from  the  focal 
center  of  the  telescope.  In  mine- 
instruments  this  arrangement  is  very 
convenient,  light  and  efficient  for 
the  establishment  of  water-courses, 
contours,  etc. 

In  Europe  special  instruments  are 
constructed  for   this  purpose;    the 
Distanzmesser  of  Stampfer,  the  gra- 
diometer  of  Stanley,  and  Short's  te- 
lemeter-level (1889),  being  notable 
examples.     Since  1894  Casella  has 
applied  the  principles  of  Shores  te- 
lemeter  to  the  miners'  dial ;  but  the         Lar850n's  Top-Mescope. 
instrument  is  without  provision  for  the  observation  of  anything 
but  gentle  gradients. 

Somewhat  earlier,  the  manner  of  attaching  the  side-telescope 
was  also  improved.  The  transverse  axis  of  the  main  telescope 
was  extended  to  end  in  a  threaded  hub,  upon  which  the  side- 
auxiliary  was  screwed  with  a  coupling-nut,  very  similar  to  the 
Gurley  method  of  securing  the  top-telescope,  and,  we  may  say, 
attended  with  very  nearly  the  same  difficulties.  After  attach- 
ing it  loosely,  and  revolving  the  auxiliary  by  hand  until  its 
horizontal-wire  should  cut  the  same  point  with  the  main  tele- 
scope, it  was  a  matter  of  some  perplexity  to  tighten  the  hub 
while  it  remained  in  this  position,  and  a  matter  of  speculation 


*  Elementeder  Vermessungskunde,  C.  M.  Bauernfeind,  Miinchen,  (1856  to)  1890, 
pp.  417,  422. 


42 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


whether  it  would  long  remain  that  way.  Fig.  38  shows  an 
admirable  feature  in  what  are  known  as  "  disappearing  stadia." 
These  were  invented  in  1880  by  Hon.  Verplanck  Colvin,  Super- 
intendent of  the  New  York  State  Survey,  to  overcome  the 
liability  of  error  in  leveling  with  the  wrong  hair.  He  caused 
Gurley  to  put  the  stadia-hairs  upon  a  separate  diaphragm,  so  as 
to  be  entirely  out  of  focus  when  not  in  use.  They  are  very 

FIG.  38. 


A  Modern  Gurley  Mine-Transit  with  Solar  Attachment  and 
"Disappearing  Stadia." 

desirable  in  all  instruments,  and  particularly  so  in  mine-transits, 
where  so  much  depends  upon  correct  vertical  angles.  As  early 
as  1865,  B.  S.  Lyman  used  glass  stadia-rods  in  the  coal-mines 
of  Pennsylvania  to  avoid  chaining  through  mud.*  They 
might  have  been  used,  however,  in  Europe  at  a  much  earlier 
date  by  engineers  who  chose  to  employ  such  aids. 

In   1778  William  Green,  a  London  optician,  published  an 

•*  Jour.  Frankl.  Inst.,  3d  series,  vol.  lv.,  1868,  p.  384. 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS.  43 

account  of  the  possibilities  of  "  subtense  measurement "  with 
either  fixed  or  adjustable  micrometer-lines  in  the  focus  of  the 
eye-piece.  Possibly  he  got  his  ideas  indirectly  from  William 
Gascoign,  of  Yorkshire,  who  is  said  to  have  devised  in  1639 
a  micrometer  for  astronomical  instruments  consisting  of  two 
pointers  traveling  by  screw-threads  in  opposite  directions. 

~No  practical  use,  however,  was  made  of  these  discoveries 
until  1824,  when  Major  M.  Porro,  of  the  Piedmontese  Army 
Engineers,  designed  the  topographometric  instrument  with 
anallactic  telescope,  which  he  named  the  "  Cleps."  Its  first 
notable  application  was  in  the  topographical  survey  of  Switzer- 
land in  1836.  It  is  now  largely  used  for  military  reconnais- 
sances in  Germany,  being  supplied  by  A.  Salmoiraghi,  of 
Milan. 

Prof.  Baker  says  :  "  Stadia-hairs  were  not  introduced  in 
America  until  after  the  Civil  War,  and  have  not  yet  come  into 
the  general  use  their  merits  warrant."* 

One  other  distinctive  feature  of  the  Gurley  instrument  here 
considered  is  the  solar  attachment.  This  is  essentially  a  Burt 
solar,  but  was  remodeled  by  William  Schmoltz,  of  San  Fran- 
cisco, in  1867,  and  has  been  mounted  since  1874  upon  the  hub  of 
the  main  telescope,  with  trivet-adjustment  to  secure  the  vertical- 
ity  of  the  polar  axis.  The  polar  axis-spindle,  with  hour-circle,  is 
permanently  fixed,  as  shown  in  Fig.  38,  to  the  main  telescope, 
to  which  the  solar  is  attached  at  will,  and  upon  which  it  re- 
volves, precluding  the  use  of  anything  but  a  semicircular  verti- 
cal arc,  which,  for  the'purpose  of  laying  off  latitude,  is  ample. 

The  original  solar  compass  was  invented  in  1836  by  William 
A.  Burt,  of  Michigan,  as  the  result  of  an  effort  to  overcome 
the  annoying  defects  of  the  magnetic  needle.  It  was  first 
made  for  him  by  Young,  and  mounted  upon  a  simple  ball- 
and-socket  base  without  tangent-screws.  Concerning  it  Prof. 
Baker  says  :  "  It  was  a  very  ingenious  instrument,  and  while, 
at  the  time,  it  deserved  the  popularity  it  attained,  it  now  re- 
flects more  credit  upon  the  inventor  than  the  one  who  uses 
it,  as  it  possesses  possibilities  of  error."  But  Capt.  Talcott,  in 
a  letter  to  Mr.  Burt,  testified  that,  in  running  the  boundary-line 
between  Iowa  and  Minnesota,  he  could  not  detect  in  the  line  it 

*  Engineers'  Surveying  Instruments,  Ira  O.  Baker. 


44 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 


FIG.  39. 


established  any  variance  with  the  most  careful  astronomical 
observations. 

Its  operation  is  always  more  perfect  in  clear  weather ;  on 
dark  or  cloudy  days  it  is  impracticable,  and  when  the  sun  is 
partly  obscured  its  image  is  indistinct,  leaving  room  for  doubt. 
In  1878  C.  L.  Berger  proposed  a  remedy  by  substituting  for  the 
lens-bar  a  small  telescope  of  low  power,  but  G.  !N".  Saegmuller 

first  made  this  practical  in  his 
excellent  invention  of  1881,  con- 
sidered on  page  729. 

In  the  meantime  English  engi- 
neers and  mathematical  opti- 
cians had  made  such  progress 
as  the  exigencies  demanded  and 
the  limitations  permitted.  In 
1857,  John  Archbutt  &  Sons, 
of  London,  had  built  for  H.  D. 
Hoskold  an  instrument*  (Fig. 
39)  constructed  upon  principles 
prevalent  in  American  types, 
which  are  at  this  day  fast  super- 
seding the  older  English  models. 
In  this  instrument  the  upper 
plates,  carrying  the  standards 
and  compass,  were  made  to  pro- 
ject somewhat  beyond  the  hori- 
zontal limb,  permitting  the  use 
of  a  4J-inch  needle  with  a  5- 
inch  circle. f  The  full  vertical  circle  was  provided  with  three 
vernier  arms,  and  the  horizontal  graduations  were  beveled  and 
unprotected ;  a  practice  still  common  in  England,  but  rare  in 
America.  The  verifying  telescope  had  been  in  use  in  the  latter 
half  of  the  last  century  to  insure  the  stability  of  astronomical 
transit  instruments,  but  Hoskold  was  first  to  use  it  with  a  mine- 
transit.  It  had  been  mounted  in  small  bearings  clamped  to  the 


Hoskold' s  Miners'  Transit- 
Theodolite. 


*  Practical  Treatise  on  Mine,  Land  and  Railway  Surveying,  H.  D.  Hoskold, 
London,  1863  ;  also,  Trans.  So.  Wales  Mm.  Engrs.,  vol.  iv.,  No.  5,  1865. 

f  Prac.  Treat,  on  M.,  L.  and  Ry.  Surveying,  H.  D.  Hoskold,  London,  1863; 
also  Trans.  So.  Wales  Mining  Engrs.,  vol.  iv.,  No.  5,  1865 ;  also  A  Treat,  on  Mine 
Sur.,  B.  H.  Brough,  London,  1888. 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


45 


FIG.  40. 


side  of  the  vertical  axis  until  1863,  when  he  invented  the  means 
of  mounting  it  concentrically,  directly  under  the  center  of  the 
plates,  so  that  its  optical  axis  should  coincide  with  the  zero-line 
of  the  horizontal  plates.  In  this  way  it  has  been  conveniently 
used  for  back-sights  without  stopping  at  each  observation  to 
clamp  the  zero  of  the  vernier  to  the  zero  of  the  limb.  The 
compound  spindles  being  thus  replaced  by  the  verifying  tele- 
scope, the  azimuth  axis  is  inverted  between  the  standards  and 
the  vertical  axis  placed  below.  An  instrument  of  this  kind 
with  two  vertical  arcs  and  striding  compass  was  exhibited  in 
the  British  section  at  the  Columbian  Exposition  in  1893. 

In  1874,  two  years  after  the  passage  of  the  Mines  Act,  which 
regulated,  among  other  things, 
correct  mine-mapping,  Stanley, 
at  the  suggestion  of  Mr.  W. 
Preece,  mounted  a  telescope 
in  Y's  upon  the  Hedley  dial. 
The  swinging  limb  still  carried 
the  vertical  arc,  now  in  an  up- 
right position,  so  as  not  to 
interfere  with  the  leveling- 
screws,  and  could  be  inclined 
to  observe  angles  of  depression 
as  great  as  55°  before  the  tri- 
pod-head interfered.  Such  an- 
gles were  determined  to  the 
nearest  degree  only,  by  a  sim- 
ple index. 

The  horizontal  circles,  however,  were  graduated  to  read  to 
3',  and  the  4J-inch  needle  to  J°.  The  eye-piece  was  inverting, 
and  the  telescope  had  a  power  of  10  diameters.  The  instru- 
ment shown  in  Fig.  40,  which  possibly  represents  the  highest 
modern  refinement  in  English  circumferenters,  is  provided  with 
the  Hoffman  quick-leveling  head,  as  modified  and  improved  by 
Prof.  J.  H.  Harden  of  the  University  of  Pennsylvania  in  1879.* 
It  was  first  invented  and  patented  in  1878  by  Daniel  Hoffman, 
of  Pottsville,  Pa.,  and  was  justly  considered  an  improvement 
over  the  designs  of  Pastorelli  (1863)  and  of  Doering  (1864). 


Telescopic  Hedley  Dial. 


Trans.,  vii.,  308. 


46 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


Davis  of  Derby  introduced  in  1882  a  modification  of  this 
improved  Hedley  dial,  in  which  he  made  the  vertical  arc  to 
be  replaced  by  a  fixed  circular  box  only  1  j  inches  in  diameter, 
with  an  index-finger  traversing  the  graduated  disk.  It  is  nec- 
essarily divided  very  coarsely  and  made  thus  compact  so  as 
not  to  interfere  with  the  easy  manipulation  of  the  leveling- 
screws.  Its  peculiar  construction  makes  it  possible  to  swing 
the  limb  in  altitude  only  about  15°  each  way.  Prof.  Brough 
says  this  is  the  best  instrument  for  colliery  use,  and  we  can 
only  infer  that  vertical  angles  must  be  of  little  consequence 
to  the  English  engineer  generally.  Certain  English  engi- 
neers are  also  still  doubtful  about  the  beneficial  use  of  the 
telescope  in  conjunction  with  the  compass  for  mine-surveying, 
seeming  to  agree  with  Gillespie,*  who  says  "  the  exactness  of 
the  vision  of  a  telescope  is  rendered  nugatory  by  want  of  accu- 
racy in  the  compass  and  the  precision  possible  in  reading  the 

needle,"  and  does  not  there- 
fore consider  it  an  improve- 
ment over  the  common 
sights  for  the  ordinary  exe- 
cution of  magnetic  surveys. 
As  late  as  1882  Stanley 
built  a  prismatic-compass 
dial  (Fig.  41)  to  conduct 
surveys  in  a  30-inch  coal- 
seam.  The  original  pris- 
matic compass  was  invented 
by  Capt.  Henry  Cater,  about 
1814,  but  this  adaptation  of 
it  for  mine-work  is  unique. 
"Where  space  in  height  is 
cramped  the  needle  is  read 
from  the  side.  The  5-inch 
compass  has  attached  to  the 


FIG.  41. 


Prismatic  Compass-Dial. 


needle  a  floating  disk  of  celluloid,  upon  which  the  magnetic 
bearings  are  read  to  the  nearest  £°  simultaneously  with  the 
observation  through  the  sights. 

The  illumination  is  effected  by  prismatic  reflection  of  light 


*  Treatise  (m  Land  Surveying,  W.  M.  Gillespie,  N.  Y.,  1856. 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


47 


FIG.  42. 


from  the  lamp  L,  as  in  the  ship's  compass.  The  combined 
weight  of  instrument  and  tripod  is  8  pounds.  The  cylindrical 
tripod-legs  contain  screw-threads,  which  are  used  for  leveling 
the  instrument.  This  device  was  patented,  but  never  became 
popular. 

The  telescope,  no  doubt,  came  into  use  with  the  more  wide- 
spread application  of  u  fast-needle  "  dialing,  as  originally  em- 
ployed by  Fenwick  in  England. 

The  magnetic  bearing  of  the  first  course  alone  is  observed, 
and  that  of  all  succeeding  courses  is  computed  from  azi- 
muth survey  by  use  of  the  vernier-plates.  It  is  then  platted 
by  calculated  tangents,  or  by  what  is  considered  in  England 
the  most  reliable  of  all  methods — the  use  of  co-ordinates  of  lati- 
tude and  departure  deduced  from  the  traverse-tables.*  This  is  a 
very  old  practice.  In  1791  John  Gale  published  traverse- 
tables  in  London,  but  they  had  been  used  from  personal  manu- 
script as  early  as  1635,  by 
Norwood,  in  the  conduct  of 
surveys  between  York  and 
London. 

Returning  to  the  discus- 
sion on  the  Burt  solar,  it 
must  be  observed  here  that 
this  instrument  came  into 
extensive  use  on  Government 
surveys  in  the  subdivision  of 
public  lands.  It  occasionally 
took  the  place  of  the  com- 
pass on  the  ordinary  transit ; 
but  the  revolution  of  the  tele- 
scope, and  the  shadow  it  cast, 
interfered  somewhat  with 
successful  operation.  To 
overcome  this  difficulty  F. 
R.  Seibert,  then  connected 
with  the  U.  S.  Coast  Survey, 
designed  a  transit  in  which  the  standards  were  inclined  for- 
ward, throwing  the  hub  of  the  telescope  just  over  the  edge 


Transit  with  Inclined  Standards. 


*  Mine  Surveys,  F.  J.  Franklands,  London,  1882. 


48  THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

of  the  plates,  in  a  position  to  leave  the  solar  open  without 
obstruction  to  the  rays  of  the  sun.  This  instrument  was 
made  for  him  by  Young,  and  was  exhibited  at  the  Centennial 
Exhibition  in  1876.  For  several  reasons,  however,  it  was  not 
a  success  for  the  purposes  intended';  but  in  1874,  at  the  sug- 
gestion of  T.  S.  McNair,  of  Hazleton,  Pa.,  it  was  converted 
into  a  mining-transit  (Fig.  42),  which,  as  such,  possessed  some 
interesting  features.  It  was  capable  of  perfect  adjustment,  and 
fulfilled  in  a  measure,  as  did  Draper's  instrument,  the  functions 
of  both  main  and  top-telescope.  Its  construction  did  not  inter- 
fere with  the  direct  and  perfect  reading  of  horizontal  angles, 

•    FIG.  43. 


Blattner.'s  "Hinged  Standards." 

though  a  counterweight  was  always  required  to  preserve  the 
equilibrium  necessary  in  the  best  instrumental  construction. 
The  eye-prism  is  detachable  at  will.  It  is  inserted  between  the 
two  lenses  of  the  ocular,  forming  an  image  that  becomes 
erect  with  respect  to  altitude,  but  reversed  in  azimuth. 
Except  by  the  use  of  a  diagonal  eye-piece,  a  steep  angle  of 
elevation  can  be  observed  only  in  a  reversed  position  of  the 
telescope  ;  but  its  one  disadvantage  lies  in  the  fact  that  in  the 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 


49 


prolongation  of  an  inclined  shaft-alignment  it  cannot  be  checked 
by  reversed  sights.  In  such  cases  one  must  rely  solely  upon 
the  perfect  adjustment  of  the  instrument. 

In  1883,  Henry  Blattner,  of  St.  Louis,  Mo.,  undertook  to 
overcome  this  objection  by  introducing  what  have  since  been 
commonly  known  as  Blattner's  "  hinged  standards  "  (Fig.  43), 
though  they  were  not  hinged  at  all.  "  The  vertical  arc  was  of 
an  entirely  new  pattern,"  he  says,  "  built  very  strongly,  so  as  to 
support  the  standards  in  any  position  of  inclination  by  a  clamp 
and  opposing  tangent-screws."  The  solar  was  mounted  upon  a 
pin  protruding  from  the  standards  in  such  a  manner  that  the 
latitude  could  be  laid  off  on  the  vertical  arc  and  the  telescope 
permitted  to  move  in  altitude  independently  of  the  solar.  In 
Blattner's  first  mineral  surveyor's  transit,  of  which  accounts 
were  published  in  the  Engineering  News,  the  telescope  was  7J 
inches  long,  provided  with  adjustable  stadia;  the  needle  was  3J 
inches  long ;  and  both  circles  were  graduated  to  read  minutes. 

Blattner's  style  of  vertical  arc,  with  the  method  of  clamping 
to  it  the  combined 
weight  of  the  stand- 
ards and  telescope,  was 
not  unlike  the  English 
model  we  noticed  in 
Fig.  40,  which,  how- 
ever, presents  the  dis- 
advantage of  having 
no  slow  tangent-move- 
ment. 

All  my  readers  will 
conclude,  no  doubt, 
that  any  instrument  in 
which  the  center  ot 
gravity  of  the  telescope 
is  so  far  removed  from 
its  support,  and  depend- 
ing for  its  stability  upon 
a  clamp,  is  of  defective  design;  and  some  will  concur  with 
Hoskold  in  the  opinion  that,  in  general,  "  this  mode  of  con- 
struction is  clumsy,  inconvenient  and  unsightly." 

Such   opinions  to  the  contrary  notwithstanding,  we    must 


Batterman's  Transit. 


50  THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 

aver  that,  while  no  essentially  eccentric  type  is  without  faults, 
that  of  Young  (Fig.  42)  possesses  the  least.  It  may  be  called 
the  "  American  Eccentric,"  and  finds  favor  in  many  localities. 
The  most  recent  design  of  this  type  is  that  built  by  the  A. 
Lietz  Co.,  of  San  Francisco  (Fig  44).  Concerning  it,  Mr.  0. 
von  Geldren  says : 

"This  transit  was  designed  by  C.  S.  Batterman,  E.M.,  of  Aspen,  Colo.,  in 
1894.  The  principles  involved  are  not  new,  but  his  application  of  them  is  unique  ; 
and  for  the  work  of  transmitting  a  point  to  extreme  positions  in  the  nadir  this 
instrument  has  given  excellent  results.  It  is  properly  balanced  by  a  counter- 
weight, and  provided  also  with  a  socket  on  a  movable  arm,  in  which  a  candle  may 
be  placed  in  any  convenient  position. 

The  eye-piece  prism  is  also  attached  to  a  movable  arm  by  which  it  is  kept 
always  at  hand  without  fear  of  losing  it,  and  can  be  laid  back  against  the  tele- 
scope when  not  in  use.  The  spring-key  between  the  leveling-screws  assures  the 
immovable  position  of  the  base-plates  to  the  tripod-coupling  which  Lietz  has 
recently  introduced.  In  it  the  usual  thread  is  replaced  by  three  jaws,  constructed 
upon  the  principles  of  the  wedge,  and  locks  by  friction  very  firmly  into  grooves 
in  the  base-plates  made  to  receive  them.  No  manner  of  attaching  an  instrument 
to  the  tripod  can  be  more  convenient  or  safe." 

Since  1896,  instruments  of  this  class  have  been  constructed 
upon  the  "  cyclotomic  "  principle,  in  which  the  double  com- 
pound spindle  is  replaced  by  a  single  axis  of  revolution,  while 
the  admirable  qualities  of  repetition  are  still  preserved  by  a 
floating  exterior  ring,  carrying  only  the  numbers,  which  may 
be  clamped  in  any  position  with  respect  to  the  horizontal 
circle.  In  this  way  any  degree-line  may  be  made  the  zero- 
point. 

Lietz  credits  the  inception  of  this  idea  to  Luther  Wagoner, 
C.E.,  of  San  Francisco,  who  found  errors  as  great  as  3'  in  90° 
in  instruments  the  compound  spindle-centers  of  which  were 
not  coincident.*  The  method  of  repetition,  in  order  to  deter- 
mine the  measured  arc  with  greater  accuracy,  was  introduced 
by  Prof.  Tobias  Mayer,  of  Gottingen,  in  1752,  and  a  little  later 
by  Borda,  under  the  name  of  "  Double  Repetition  or  Multipli- 
cation." Mr.  Wagoner  did  not  wish  to  abolish  this  practice, 
but  to  introduce  a  new  and  safer  means  of  accomplishing  the 
same  result. 

In  1881,  G.  N.  Saegmuller,  of  Washington,  D.  C.,  who  con 
ducts  the  instrumental  establishment  of  Fauth  &  Co.,  introduced 

*   Trans.  Tech.  Soc.  of  the  Pac.  Coast,  vol.  vii. ,  No.  5. 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 


51 


FIG.  45. 


his  telescopic  solar  attachment  (Fig.  45),  which  Prof.  J.  B. 
Johnson  says  "is  accurate  beyond  any  disk-attachment,  and 
represents  the  correct  solution  of  the  solar-attachment  prob- 
lem." The  standards,  in  which  the  solar  telescope  may  be 
elevated  or  depressed,  are  free  to  revolve 
about  the  polar  axis,  and  are  governed  by 
the  usual  clamp-and-tangent  movement. 
The  polar  axis  is  adjusted  by  trivets  at 
its  base-mountings  to  be  at  right  angles 
to  the  line  of  collimation  and  transverse 
axis  of  the  main  telescope.  When  the 
transit  and  attachment  are  in  perfect  ad- 
justment, its  operations  are  quite  pre- 
cise. The  objections  to  it  are  mainly  the 
possible  errors  of  the  observer  in  allow- 
ing for  declination,  latitude  and  refrac- 
tion; but  very  careful  manipulation  will 
reduce  the  azimuth  of  the  meridian  de- 
termined with  that  of  the  astronomical 
l^orth  to  a  few  seconds.  The  original 
attachment  was  light  in  weight  and  of 
low  telescopic  power  ;  but  when  Ameri- 
can mine-surveyors  began  to  employ  it  Saegmuller's  Telescopic  So- 
in  place  of  the  top-telescope  its  size  was  lar> in  Use  as  a  Top-Aux- 
considerably  increased,  and  the  power  of 

the  telescope  raised  to  18  diameters,  as  shown  in  Fig.  45.  As 
used  for  this  doable  purpose  it  must  be  looked  upon  as  the  first 
top-auxiliary,  the  adjustment  of  which,  for  parallelism  by  means 
of  the  base-trivets  and  for  alignment  by  means  of  the  clamp-and- 
tangent  movement,  could  be  tested  and  secured  by  the  operator 
For  vertical  sighting  it  has  one  inconsiderable  fault,  to  be  dis- 
cussed later,  which,  in  comparison  with  its  other  admirable 
features,  cannot  be  justly  said  to  militate  against  its  success- 
ful operation.  The  mining-transit  shown  in  Fig.  45,  having 
4-inch  circles,  graduated  to  read  minutes,  and  provided  with 
interchangeable  eye-pieces  to  regulate  power  and  light  to  suit 
the  conditions,  must  be  regarded  as  one  of  the  best  examples 
of  perfect  instrumental  construction. 

In  1885,  to  meet  the  ever-prevailing  demand  for  increase^ 
efficiency  combined  with  smaller  weight,  Saegmuller  introduced 

5 


52  THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 

in  America  the  plain  detachable  object-prism,  which  was  used 
for  a  time  for  vertical  sighting,  in  place  of  auxiliary  telescopes, 
but  was  found  to  be  more  alluring  than  satisfactory.  When  it 
was  simply  fitted  to  the  object-glass,  like  a  sun-shade,  the  45° 
mirror  it  contained  reflected  rays  truly  at  right  angles  to  the 
line  of  sight,  but  whether  or  not  in  absolute  vertically  was 
sheer  assumption,  and  the  slightest  variation  from  the  correct 
position  doubled  the  deviation  of  the  emergent  rays. 

This  was  remedied  to  some  extent  by  setting  a  small  pillar 
into  the  collar  of  the  objective,  and  so  attaching  small  opposing 
screws  to  the  prism  that  they  could  be  made  to  work  upon  the 

pillar.  In  this  way  the  po- 

FIG.  46.  *.  .  J        F 

sition  or  the  prism  could 

be  regulated  very  care- 
fully ;  but  to  secure  for 
it  absolute  vertically  was 
an  operation  that  involved 
more  time  and  trouble 
than  most  engineers  are 
willing  to  take. 

Prof.  Steinheil,  of  Mu- 
nich, first  used,  in  1847, 
for  astronomical  obser- 
vations, the  object-prism 
attached  to  a  meridian 
instrument.  Later,  M. 

d'Abbadie,  of  Paris,  employed  it,  rigidly  attached  to  a  small 
traveler's  theodolite  (Fig.  46),  constructed  like  a  Y-level, 
mounted  upon  a  circle.  The  vertical  limb  of  his  instrument 
encircled  the  telescope  at  the  eye-end.  In  this  way  the  zenith 
or  nadir  position  of  the  prism  was  determined  by  bringing  the 
vertical  circle  to  read  0°  or  180°  upon  its  vernier. 

Before  the  objective  prism  came  into  use,  rays  were  deflected 
by  means  of  an  ordinary  mirror,  held  in  the  hand,  or  by  at- 
taching to  the  objective  collar  a  mirror-plate,  movable  upon  a 
hinge,  so  as  to  be  set  at  any  angle.  In  this  way  Borchers  con- 
ducted shaft-surveys  in  1844  at  Clausthal;  but  the  observation 
of  an  object  at  any  but  a  right  angle  made  the  calculations 
complicated. 

Last  year  (1897)  Saegmuller  brought  to  perfection  the  con- 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


53 


FIG.  47. 


Double-reflecting  Objective 
Prism. 


FIG.  48. 


struction  of  the  objective  prism.  His  design  is  intended  to 
utilize  the  optical  law  that  a  ray  which  has  been  reflected  twice 
in  the  same  plane  makes,  after  its  second  reflection,  an  angle  with 
its  original  direction  equal  to  twice  the 
angle  made  by  the  reflecting  surfaces  with 
each  other.  The  double  45°  reflecting- 
prism  (Fig.  47),  then,  will  project  rays 
in  true  vertically  when  the  transit- 
telescope  is  placed  horizontally,  whether 
the  prism  be  fitted  in  exact  adj  ustment 
or  not.  Therefore  the  work  of  this  prism 
in  transmitting  vertical  sights  will  be  as 
perfect  as  it  is  possible  to  make  the  ad- 
justment of  the  telescope  to  horizontal- 

ity.  As  used  on  American  instruments,  the  objective  prism 
now  has  but  one  disadvantage.  It  is  obvious  that  any  neces- 
sary movement  of  the  object- 
glass  in  focussing  destroys  the 
line  of  sight,  and  renders  vari- 
able what  should  be  a  fixed 
eccentricity  of  collateral  sight- 
ing. Its  most  successful  ope- 
ration, therefore,  is  only  with 
the  German  or  French  instru- 
ments, which  are  focussed  by 
movements  of  the  ocular. 

The  most  remarkable  of  mod- 
ern applications  of  the  prism 
to  mine-transits  abroad  is  ex- 
emplified in  the  instrument 
(Fig,  48)  introduced  by  Fric 
Brothers,  of  Prague,  Bohemia, 
in  1886.*  It  is  claimed  by  the 
makers  to  be  an  improvement 
over  all  other  types,  to  reduce 
the  errors  of  eccentricity  to  a 
minimum,  and  to  overcome  the 
cumbersome  features  prevalent  in  most  other  German  instru 


Fric  Mine-Theodolite. 


Zeitschrifi  fur  Instrumentenkunde,  Berlin,  vi.,  221,  1886. 


54 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


FIG.  49. 


ments.  The  transverse  axis  of  the  main  telescope  is  enlarged 
and  perforated  in  a  manner  similar  to  Hohnbaum's  Grosses 
Niveau*  so  as  to 'become  a  secondary  telescope  for  steep  sight- 
ing. At  its  outer  extremity  is  rigidly  attached  a  prism,  inter- 
mediate between  the  objective  and  ocular,  after  the  fashion  of 
the  "  broken  telescope  "  of  Eeichenbach.  It  is  focussed  upon 
distant  objects  by  a  sliding  movement  of  the  ocular,  as  in  the 
mariners'  spy-glass,  and  the  barrel  is  constructed  to  taper  to- 
wards the  eye-piece  according  to  the  scientific  principle  of  the 

convergence  of  the  rays  of  light  in  pass- 
ing through  a  lens.  The  sliding  ocular 
contains  the  diaphragm  and  cross-hairs, 
which  are  protected  from  moisture  on 
each  side  by  hermetically  sealed  thin 
glass  disks ;  and  if  by  chance  any  dust- 
particles  should  settle  upon  them,  no  dif- 
ficulty is  experienced,  as  the  ocular  is 
not  focussed  upon  the  plane  in  which 
they  lie.  Spider-webs  are  hygrometric, 
being  sensibly  affected  by  the  humidity 
of  the  atmosphere,  to  the  extent  of  de- 
ranging the  line  of  collimation.  For 
this  reason  Fric  suggests  that,  except 
for  the  collection  of  dust  and  dew,  the 
occasional  German  practice  of  using  for 
the  diaphragm  a  thin  glass  disk,  with 
delicately  etched  cross-lines  upon  its 
surface,  should  take  the  place  of  spider- 
webs  entirely.  The  main  telescope  has 
a  focal  length  of  17  cm.,  and  is  provided  with  a  longitudinal 
bubble,  clamped  to  its  upper  surface,  that  must  be  removed 
whenever  the  telescope  is  to  describe  a  complete  revolution. 
The  horizontal  circle  is  made  of  thick  plate-glass.  Its  gradua- 
tions are  etched  somewhat  back  from  its  outer  edge,  and  read 
by  means  of  the  Hensold  prismatic  glass  micrometer  with  the 
assistance  of  reflected  light  from  the  prism  (s)  beneath.  The 
needle  is  placed  in  a  box  (M )  outside  the  standards,  to  econo- 
mize space  and  weight.  It  is  mounted  eccentrically  at  |-th  oi 


Breithaupt's  Orientation- 
Instrument. 


*  Die  Geometrischen  Instrumente,  Hunaus,  p.  408. 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS,  55 

its  length  from  one  end,  and  balanced  by  a  small  counter- 
weight, so  as  to  give  the  greatest  sensitiveness  within  the  avail- 
able space. 

We  notice  here  another  evidence  of  the  decline  in  the  use 
of  the  magnetic  needle,  though  for  the  work  of  orientation  a 
very  precise  instrument  was  introduced  by  Breithaupt  in  1887* 
(Fig.  49).  The  needle  in  this  case,  which  is  of  more  than  ordi- 
nary length  and  sensitiveness,  is  designed  to  take  the  place  of 
the  magnetometer  of  Borchers  (1846),  which  was  suspended  by 
a  silken  thread  before^  the  objective  of  the  telescope  and  used 
to  determine  exactly  the  magnetic  meridian  in  mines.  The 
most  remarkable  of  such  magnetic  surveys  known  to  the  writer 
was  the  extension  of  the  Ernst- August  adit-level  in  the  upper 
Harz,f  through  a  space  of  4753  yards,  with  a  final  error  of 
only  8  inches  in  elevation  and  1  minute  8  seconds  in  azimuth. 
Owing  to  dense  forests  between  the  shafts,  their  relative  posi- 
tions were  deduced  from  the  Ordnance  survey  in  1876.  This 
is  probably  the  first  instance  in  which  any  government  survey 
has  served  as  the  basis  for  important  underground  work. 

The  orientation-instrument  can  be  provided  with  a  vertical 
circle  to  adapt  it  to  a  wider  range  of  work,  or,  as  made  by 
Tesdorpf,  with  a  side-auxiliary  telescope,  counterbalanced  by  a 
bracket-lamp.  As  originally  built,  however,  it  was  intended 
only  as  a  supplementary  instrument. 

The  15-cm.  needle  is  mounted  upon  a  ruby  concentrically 
with  the  horizontal  circle,  and  the  meridian  line  of  the  base  is 
in  the  same  plane  with  the  line  of  collimation.  By  use  of  the 
additional  objective-lens  (A)  the  telescope  is  transformed  to  a 
microscope,  and  in  this  way  used  for  the  very  precise  view- 
ing of  the  needle.  This  makes  it  a  superior  instrument  to 
those  provided  with  the  usual  form  of  striding-compass,  the 
concentricity  of  which  with  the  instrument  is  not  always  reli- 
able. The  striding-compass,  as  applied  to  mine-instruments, 
was  first  used  in  Germany  in  1837 ;  but  its  original  inventor  is 
not  known.  Brander  describes  them  as  early  as  1780,  in  con- 
nection with  sun-dials. 

In    1889   BufF  &   Berger   introduced   it   in   America  with 


*  Der  Bergbau,  No.  24,  1888;  also  Cours  de  Topographic,  A.  Habets,  Liege,  1895. 
f   Berg-  und  Hilttenm.  Zeit.,  li.,  293,  Aug.  12,  1892. 


56  THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

their  duplex-bearing  mine-transit  (Fig  50),  as  made  for  George 
W.  Robinson,  of  Marysville,  Mont.  In  this  instrument  vertical 
sighting  could  be  accomplished,  with  the  main  telescope  in  a 
position  that  corresponded  to  the  inclined  standards  of  Young, 
by  removing  the  telescope,  with  all  its  adjuncts,  from  its  normal 
to  its  secondary  bearings,  which  were  very  carefully  constructed, 
being,  in  fact,  cast  into  one  piece  with  the  standards.  When  in 
this  position,  a  4-pound  counterpoise  was  attached  to  the  plates 
at  W. 

Later,  Keuffel  &  Esser,  of  New  York,  and  Fauth  &  Co.,  of 
Washington,  each  designed  instruments  of  this  class,  as  illus- 

•    FIG.  50. 


Buff  &  Berger's  Duplex-Bearing  Mine-Transit. 

trated  in  Figs.  51  and  52,  but  have  found  that  their  construc- 
tions violated  the  principles  which  ought  to  be  observed  in  a 
perfect  transit>instrument.  Such  conveniences  as  they  afford 
are  hardly  commensurate  with  the  risk  of  getting  the  delicately- 
adjusted  bearings  full  of  grit  underground  while  making  the 
transposition.  "  Besides,"  says  Saegmuller,  "  the  instrument 
was  too  heavy  and  too  expensive."  His  instrument  weighed 
25  pounds  complete.  The  secondary  bearings  were  not  per- 
manently fixed  to  the  instrument,  but  contained  in  side-arms 
that  were  attached,  when  necessary,  by  thumb-screws  to  the 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 


57 


upper  part  of  the  standards.  To  this  instrument  he  added 
his  quick-leveling  attachment,  patented  in  1879.  It  consisted 
of  two  wedge-shaped  disks,  traveling  upon  each  other  in  a 
groove,  and  interposed  between  the  plates  and  tripod-head. 

This,  with  the  quick-leveling  heads  of  Gurley  (1878),  con- 
structed upon  the  principles  that  obtain  in  the  designs  of  Pas- 
torelli  and  Hoffman-Harden,  and  the  detachable  ball-and-socket 
quick-leveling  head  of  Buff  &  Berger  (1883),  represent  the 
American  achievements  along  this  line. 

FIG.  51. 


Duplex-Bearing  Mine-Transit,  Keuffel  &  Esser. 

The  concentric  model  of  mine-instrument  with  the  American 
supplementary  telescope  must  eventually  supersede  the  types 
of  Borchers  and  Combes  abroad ;  but  the  popularity  of  the 
eccentric  instrument  in  Germany  still  continues.  That  re- 
cently made  by  Ludwig  Tesdorpf,  of  Stuttgart  (Fig.  53),  is  one 
of  the  few  provided  with  micrometer-microscopes  and  detach- 
able vertical  circle.  It  has  a  12-cm.  horizontal  circle,  reading 
to  1.0",  and  a  10-cm.  vertical  circle  reading,  by  vernier, 
to  1'. 


58 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 


Between  the  standards  is  a  circular-box  bubble   for  leveling 
the  instrument,     The  micrometer-microscope  is  practically  the 
FIG.  52.  original  design  of  Troughton,  in 

which,  briefly,  the  distance  be- 
tween any  degree-line  and  the 
index  of  the  limb  is  carefully 
measured  by  a  sliding  scale  that 
passes  through  the  mutual  focus 
of  the  objective  and  the  ocular. 
This  is  operated  by  a  milled-head 
screw,  of  such  fineness  that  one 
revolution  corresponds  to  10'  of 
arc.  Each  of  the  sixty  subdivi- 
sions of  the  graduated  head, 
then,  will  represent  10".  The 
instrument  shown  in  Fig.  53 
weighs  6  kg.,  and  its  tripod  as 
much  more. 

For  rapid  and  accurate  sub- 
tense measurement  some  engi- 
neers have  for  a  long  time  been 
at  work  on  adapting  such  mi- 
crometrical  slides  to  the  ocular  of  the  main  telescope ;  but  the 
results  of  experiments  made  in  the  great  Indian  survey  would 
seem  to  confine  its  use  still  to  the  determination  of  the  odd 
seconds  in  reading  horizontal  angles. 

Prof.  Brathuhn  has,  however,  utilized  an  immovable  scale  in 
the  diaphragm  of  the  main  telescope,  on  a  slightly  different 
principle,  that  is  intended  to  unite  the  methods  of  Dr.  Schmidt 
(p.  34)  and  the  earlier  practice  of  suspending  shaft-plumbs  in 
oil  and  guessing  at  the  probable  point  of  rest* 

The  diaphragm  he  uses  is  a  glass  plate  upon  which  the  hori- 
zontal line  is  graduated  into  subdivisions  of  such  value  that 
readings  as  close  as  one  minute  can  be  estimated.  He  does 
not  attempt  the  laborious  task  of  ranging  the  instrument  into 
exact  alignment  with  the  plumb-wires,  but  sets  up  at  some  arbi- 
trary and  convenient  station,  and,  by  watching  the  vibrations 
of  each  wire  upon  the  scale,  determines  its  angular  position 


Gea  N.  Saegmufler 

Washington.  DC 

Duplex-Bearing  Mine-Transit, 
P^auth  &  Co. 


Berg- und  Hiittenm.  Zeiturtg,  Ivi.,  395,  Nov.  19,  1897. 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS.  59 

with  reference  to  the  next  regularly  established  station  in  the 
survey.  The  difference  of  these  two  readings  will  give  the 
value  of  the  very  acute  angle  subtended  at  the  instrument  from 
the  short  base-line  between  the  wires. 

One  of  the  most  interesting  of  modern  German  mine-the- 
odolites is  the  American  pattern  of  Breithaupt,  introduced  in 
1892  (Fig.  54).  It  is  an  improvement  upon  the  generality  of 
American  instruments  in  that  the  truss-standards  (since  1880) 
have  been  cast  in  one  piece  with  the  compass-ring;  and  it  pos- 
sesses also,  in  the  construction  of  the  side-telescope,  features 
well  worthy  of  special  comment. 

FIG.  53. 


German  Eccentric  Theodolite. 

Its  spindle-hub  is  set  into  a  perforation  of  the  transverse 
axis  in  very  much  the  same  manner  as  was  customary  in  the 
first  American  model,  but  has  a  clamping-  and  tangent-device 
that  holds  it  securely,  and  quickly  ranges  it  into  alignment  with 
the  main  telescope,  where  its  position  is  verified  by  a  longitu- 
dinal bubble.  The  illumination  is  accomplished  through  the 
transverse  axis,  as  was  first  practised  by  Usser,  professor  of 
astronomy,  at  Dublin,  in  1790.  The  20-cm.  horizontal  circle  is 
graduated  to  read  by  its  verniers,  or  nonius,  as  they  are  still 
erroneously  called  by  the  Germans,  to  10".  Pedro  Nunez,  a 


60 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


FIG.  54. 


Portuguese  mathematician,  to  whom  this  compliment  is  paid, 
published  in  De  Crepusculis  Olyssipone,  1542,  a  proposal  that 
upon  the  plane  of  the  quadrant  be  described  44  concentric  arcs, 
divided  respectively  into  from  44  to  89  equal  parts.  The  single 
indicator,  then  employed,  would  coincide  more  or  less  perfectly 
with  one  of  the  subdivisions.  It  gave,  no  doubt,  very  close 

readings.  For  instance,  if  the  index 
cut  the  7th  circle  at  its  43d  gradua- 
tion, the  angle  was  read  as  |~|  of  90°, 
or  46°  4'  17|". 

The  solar  on  the  Breithaupt  in- 
strument, while  practically  the  de- 
sign of  Saegmuller,  is  one  introduced 
by  Prof.  Dr.  Schmidt  in  1892,  for 
the  use  of  American  students  at 
Freiberg.* 

Certain  engineers  took  occasion 
to  point  out  the  possibility  that  Saeg- 
muller's  solar  might  move  in  alti- 
tude upon  its  horizontal  axis  while 
in  use  for  vertical  sighting,  and  thus 
destroy  the  efficiency  of  the  base- 
trivets.  In  1895,  Buff  &  Berger 
made  for  George  T.  Wickes,  of 
Cokedale,  Mont.,  an  instrument 
(Fig.  55)  calculated  to  overcome  this 
objection  by  making  the  "polar 
axis  "  or  vertical  pillar  rigid  with  the  auxiliary  telescope,  retain- 
ing only  the  trivet-base,  in  a  new  form,  with  every  desirable  pro- 
vision to  insure  parallelism  and  alignment.  As  in  this  construc- 
tion the  setting  of  the  sun's  declination  becomes  impossible,  its 
uses  are  restricted  to  the  primary  offices  of  a  top-auxiliary  tele- 
scope ;  but  as  such,  with  its  delicate,  rapid  and  effectual  means 
for  all  necessary  adjustments,  it  represents,  no  doubt,  with 
Breithaupt's  side-auxiliary,  all  that  could  be  required  in  such 
individual  devices. 

No  matter  how  perfect  may  be  the  construction  and  means 
of  adjustment,  however,  each  of  these  appliances  has,  combined 


Breithaupt's  Mine-Theodolite. 
( American  Pattern. ) 


*  Oesterr.  Zeit.  fur  Berg-  und  Hilttenwesen,  No.  21,  1892. 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


61 


FIG.  55. 


with  its  advantages,  that  negative  condition  known  as  eccen- 
tricity, for  which  correction  must  be  allowed,  varying  with  the 
conditions  in  each  case. 

In  1896  the  writer  designed  a  mine-tachymeter  which,  as  he 
ventures  to  assert,  by  its  peculiar  yet  simple  construction,  em- 
braces the  advantages  and  eliminates  the  disadvantages  of  all 
other  types.  Its  individuality  consists  principally  in  the  inter- 
changeability  of  the  auxiliary  telescope  and  the  means  provided 
to  thus  transform  the  instrument  from  one  condition  to  the 
other,  as  shown  in  Figs.  56  and 
57. 

In  this  way  the  double  nega- 
tive quantities  become  positive 
in  their  resultant,  so  to  speak; 
and  we  have  a  mining-transit 
capable  of  performing,  with  more 
than  usual  exactness,  all  the  com- 
plex functions  required  in  mines, 
and  requiring  absolutely  no  correc- 
tions for  eccentricity. 

The  auxiliary  telescope  is  so 
provided  writh  a  hub  of  new  de- 
sign that  it  may  be  screwed 
to  the  threaded  extension  of 
either  the  transverse  axis  or  the 
vertical  pillars  of  the  main  tele- 
scope. In  this  position  it  is 
clamped  firmly  and  ranged 
quickly  into  alignment  with  the 
main  telescope  by  two  small  opposing  screws  that  work  up  an 
arm  of  the  hub.  Upon  its  diaphragm  is  but  one  web,  so  placed 
that  it  shall  be  vertical  when  on  top,  and  horizontal  when  at  the 
side.  In  either  position  the  amount  of  eccentricity  is  the  same, 
though  perfect  operation  would  not  be  affected  if  this  varied, 
since  the  observation  of  steep  horizontal  angles  is  made  only 
with  the  auxiliary  on  top,  and  of  very  precipitous  vertical  angles 
with  the  auxiliary  at  the  side. 

On  this  account,  any  adjustment  for  parallelism  in  the  op- 
tical axes  of  both  telescopes  is  dispensed  with,  as  its  peculiar 


Buff  &  Berger's  Top-Telescope, 
with  Adjusting  Trivets. 


62  THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

adaptability  will  insure  perfect  results  even  if  the  conditions  in 
FlG  56  this  particular  are  imperfect. 

I  Buff  &  Berger,  who  made  the 

instrument,  have  recently  added 
trivets  to  the  base  of  the  upper 
vertical  pillar;  but  these  are  un- 
necessary, and  impair  the  stability 
of  the  instrument. 

The  auxiliary  (Fig.  58)  has  a 
power  of  17  and  the  main  tele- 
scope of  24  diameters,  being  the 
greatest  possible  under  the  re- 
strictions observed  with  regard  to 
size  and  light.  The  amount  of 
light  received  through  the  ocular 
varies  as  the  square  of  the  diam- 
eter of  the  objective;  therefore, 
the  larger  the  aperture  in  mine- 
transits  the  more  favorable  will 
be  the  conditions  with  respect  to 
light,  provided,  however,  that 
power  be  not  sacrificed  by  the 
use  of  an  ill-proportioned  ocular. 
The  ocular  of  this  instrument  is 
inverting,  conforming  to  the  gen- 
eral practice  of  European  engi- 
neers, who  no  doubt  excel  in  this 
respect.  As  American  engineers 
become  better  acquainted  with 
their  desirable  qualities,  either 
the  Ramsden,  Kelner  or  Steinheil 
oculars  will  be  more  widely  used. 
They  all  have  the  advantage  of 
not  only  permitting  greater  light 
and  a  larger  field,  but  in  a  tele- 
scope of  the  same  size  an  objective 
Scott's  Mine-Tachymeter.  Auxiliary  of  greater  focal  length  is  permissi- 
on T°P-  ble,  thereby  favoring  the  condi- 
tions imposed  to  secure  the  best  definition.  By  thus  increasing 
the  focal  length  of  the  objective,  while,  by  virtue  of  its  construe- 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS.  68 

tion,  that  of  the  inverting  ocular  is  decreased,  the  magnifying 
power  becomes  greater. 

Both  horizontal  and  vertical  circles  are  5  inches  in  diameter, 
divided  into  half  degrees,  and  read  to  minutes.  This,  on  the 
authority  of  many  years'  practice,  and  by  general  consent,  is 
conceded  to  be  most  easily  read  underground,  and  to  be  fine 
enough  for  mine-work.  The  novice  is  generally  too  much  in- 
clined to  high  telescopic  power  and  extremely  fine  graduations, 

FIG.  57. 


Scott's  Mine-Tachy meter.     Auxiliary  at  the  Side. 

with  the  idea  that  the  greatest  accuracy  can  thus  be  attained. 
But  this  is  a  mistake.  Beside,  the  stationary  double-lens  read- 
ing-glasses that  become  necessary  to  read  such  fine  circles  only 
provide  the  means  of  invariably  burning  the  engineer's  face 
when  he  attempts  to  get  both  his  eye  and  candle  near  enough 
to  the  plates  to  take  a  correct  reading.  The  vertical  circle  is 
graduated  in  quadrants,  the  zero-line  running  parallel  with  the 
line  of  collimation,  and  is  read  by  one  double  vernier,  so  placed 


64  THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 

near  the  eye-end  that  any  angle  of  elevation  or  depression  may 
be  determined  with  the  telescope  in  a  normal  or  reversed  posi- 
tion. The  horizontal  graduations  read  only  in  one  direction, 
being  numbered  continuously  with  one  set  of  figures,  from  0°  to 
360°.  This  permits  the  verniers  to  be  single,  and  provides  a 
uniform  method  that  almost  entirely  removes  any  possibility  of 
error  in  reading,  recording,  figuring  or  platting.  The  verniers 
are  directly  under  the  telescope,  so  that  one  need  not  move  to 
read  them,  and  if  the  engineer  is  satisfied  that  his  graduations 
are  correct,  he  wrill  habitually  read  but  one  of  these,  taking 
care,  however,  to  repeat  every  angle  at  least  once ;  for  no  mine- 
surveyor  can  be  certain  of  his  work  until  he  has  checked  every 
step  by  the  same  or  different  means. 

The  U-shaped  standards  are  a  new  pattern,  designed  to  con- 
form to  American  practices  and  methods.  Being  of  one  piece 
they  are  very  rigid,  and,  as  old-time  fancies  wear  out,  will 

doubtless  come  into   general  use. 
IG'  58<  They  are  made  of  aluminum,  and 

bushed  with  electrum  at  the  bear- 
ings. Their  construction  does  not 
permit  the  use  of  the  usual  com- 
pass-box; but  in  high-class  mine- 
work  the  magnetic-needle  cannot 
seriously  be  said  to  be  essential  for 
-y  purpose  whatever.  The  hi, 
tory  of  magnetic  surveys  is  itself 
the  death-warrant  of  the  miners'  compass ;  and  in  this  age  of 
widespread  electrical  power  and  lighting  (employed  with  rap- 
idly increasing  frequency  in  mines),  the  magnetic  needle  be- 
comes no  more  reliable  in  mine-surveys  than  on  the  present 
iron-clad  man-of-war. 

Mine-surveys  are  nearly  always  figured  by  trigonometrical 
functions,  as  referred  to  the  boundary-lines ;  but  if  the  engi- 
neer prefers  to  use  the  calculation  by  latitudes  and  departures, 
a  good  practice  is  to  establish  by  stellar  or  solar  observation, 
at  one  end  of  the  base-line  in  the  surface-triangulation,  or,  bet- 
ter, at  one  of  the  boundary-corners,  a  true  meridian  from  which 
every  station  in  the  whole  system,  both  underground  and  on  the 
surface,  has  an  established  latitude  and  departure,  and  every 
course  an  established  bearing.  After  the  work  of  procuring 


THE    EVOLUTION  OF    MINE-SUKVEYING    INSTRUMENTS.  65 

and  tabulating  these  data  is  once  completed,  this  system  is  per- 
haps the  most  concise  in  subsequent  computation;  but  the 
initial  time  and  effort  it  requires  are  scarcely  repaid  by  the 
benefit  secured. 

For  such  work,  with  this  tachymeter,  the  Davis  solar  screen 
(Fig.  59)  is  doubtless  best  to  use.     It  was  invented  in  1880  by 
Prof.  J.  B.  Davis,  of  the  University  of  Michi- 
gan, who,  in  writing  to  me,  said :   "  In  my 
opinion,  my  solar  screen  requires  less  calcu-     ' 
lation  than  any  other,  if  properly  used.     Its 
work  is  even  more  precise  than  the  circles 
of  the  transit,  and  requires  no  special  ad- 
justments or  mechanical  conditions.     Some 
others  require  those  that  cannot  be  tested." 
If  used  with  an  erecting  telescope,  the  full 
aperture   of  the   objective   is   utilized;   but 
with  an  inverting  ocular,  in  order  to  obtain      Davis  Solar  Screen, 
a  clear  reflection  of  the  cross-hairs  upon  the 
screen,  a  telescope-cap  is  provided,  so  as  to  reduce  the  aperture 
to  about  J-inch. 

The  diaphragm  of  this  instrument  is  made  of  more  than 
ordinary  thickness.  Upon  one  side  are  placed  the  usual  cross- 
hairs and  upon  the  other  the  fixed  stadia-hairs,  which  are  out 
of  focus  when  not  in  use.  In  this  way,  as  explained  before  (p. 
42),  there  will  be  no  danger  of  reading  an  important  vertical 
angle  on  a  long  and  indistinct  sight  with  the  wrong  horizontal 
hair. 

The  shortest  sight  possible  with  the  telescope  of  this  mine- 
tachymeter  is  5.5  feet,  which  for  ordinary  mine-work  is  suf- 
ficient, though  occasionally  a  shorter  sight  than  this  is  una- 
voidable. In  most  German  and  French  instruments  the  ocular 
can  be  drawn  out  so  far  as  to  permit  observations  within  the 
first  meter;  but  this  plan  is  impossible  in  American  and  English 
models.  For  these,  then,  the  only  plausible  plan  for  very 
near  sighting  must  provide  for  an  additional  objective  lens,  as 
described  in  connection  with  Breithaupt's  orientation  instru- 
ment (see  A,  Fig.  49).  Such  an  arrangement  Buff  &  Berger 
are  now  perfecting  for  this  work.  It  is  provided  with  ad- 
justing-screws at  the  side,  so  that  the  center  of  the  lens  may  be 
made  to  coincide  exactly  with  the  optical  axis  of  the  telescope. 


66 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 


Otherwise,  by  the  careless  addition  of  an  extra  objective,  the 
adjustment  of  the  line  of  collimation  may  be  disturbed. 

In  designing  the  mine-tachymeter,  it  was  the  writer's  object  to 


FIG. 


The  First  American  Transit,  built  by  Young  &  Son,  Philadelphia,  1831. 

make  it  the  most  complete,  convenient,  precise  and  compact  in- 
strument yet  introduced  for  mining  engineering,  and  to  this 
end  it  was  his  intention  to  add  one  other  improvement,  which 


THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS.  67 

up  to  this  time  remains  but  a  suggestion ;  but  such  engineers 
or  makers  as  choose  to  employ  it  may  do  so  without  fear  of  in- 
terference, as  the  original  makers  are  now  seemingly  extinct. 

In  the  Eng.  and  Min.  Journal  of  November  7,  1891,  is  de- 
scribed Cook's  patent  luminous  level  tube,  which  has  an  inner 
coating  of  phosphorescent  compound,  covered  by  a  coat  of 
water-proof  lacquer,  by  which  the  bubble  is  made  to  appear  as 
distinct  against  the  graduations  in  the  tube  in  the  dark  as  in  the 
light.  As  it  frequently  happens  that,  because  the  flicker  of 
surrounding  lights  seems  to  absorb  all  dim  rays  coming  from  a 
long,  indistinct  sight,  the  engineer  prefers  to  remain  in  the 
dark,  the  use  of  such  a  device  would  enable  him  to  watch  his- 
bubbles  while  making  such  observations. 

In  ordinary  setting-up,  moreover,  it  seems  likely  that  the 
work  would  be  greatly  facilitated. 

Fig.  60,  a  picture  of  the  first  American  transit,  referred  to 
on  p.  25,  may  fitly  conclude  this  paper,  showing  how  much 
progress  has  been  made  in  the  construction  of  such  instruments 
since  that  modest  beginning,  sixty-seven  years  ago. 

The  writer  invites  correspondence  upon  the  topic  here  dis- 
cussed, for  the  purpose  of  rectifying  possible  errors  and  en- 
larging the  historical  evidence,  which  is  now  of  necessity  in- 
complete. The  subject  has  been  profusely  treated  abroad,  and 
ought  to  receive  more  consideration  on  this  side  of  the  Atlantic. 


68  THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS. 


DISCUSSION. 

SECRETARY'S  NOTE. — The  foregoing  paper  aroused  so  much 
interest  among  mining  engineers  and  manufacturers  of  survey- 
ing instruments,  that  the  Institute  has  already  been  favored 
with  the  following  painstaking  contributions  by  way  of  discus- 
sion, addressed  either  to  the  author  or  to  the  Secretary.  The 
subject  is  by  no  means  exhausted,  nor  can  it  be;  for,  aside 
from  chronicling  the  past,  doubtless  new  improvements  will 
still  continue  to  deserve  to  be  recorded.  Nevertheless,  the 
present  volume  must  necessarily  stop  somewhere.  The  Trans- 
actions^ however,  will  always  be  hospitably  open  to  further 
papers  on  the  subject.  Decision  as  to  the  propriety,  pertinency 
and  value  of  communications  offered  rests  with  the  Council  of 
the  Institute ;  but  ordinarily  those  of  members  would  take  pre- 
cedence. Manufacturers'  descriptions  of  their  instruments  will 
not  be  excluded;  except  that  pure  advertisements,  asserting 
without  defining  the  merits  of  special  devices,  would,  of  course, 
be  declined. 

BENNETT  H.  BROUGH  :*  Having  devoted  many  years  to  a 
study  of  the  history  of  mine-surveying,  some  of  the  results  of 
which  I  published  partly  in  a  course  of  lecturesf  delivered  be- 
fore the  Society  of  Arts  in  1892,  and  partly  in  a  separate 
work,J  I  consider  that  the  information  Mr.  Scott  has  got  to- 
gether to  illustrate  the  gradual  evolution  of  American  mine- 
surveying  instruments  during  the  past  sixty-seven  years  forms  a 
valuable  contribution  to  knowledge.  There  are,  however,  sev- 
eral statements  in  the  paper  that  are  open  to  criticism.  For 
example,  the  author  is  inaccurate  in  stating  that  the  use  of  the 
compass  in  mine-surveys  is  first  described  by  Agricola.  As  a 
matter  of  fact,  it  is  described  in  the  oldest  treatise  on  mining, 
a  work  written  in  German  and  published  anonymously  in  1505 

*  Formerly  Instructor  in  Mine  Surveying,  Eoyal  School  of  Mines  ;  Sec' y  Iron 
and  Steel  Institute,  28  Victoria  Street,  London,  England.  This  communication 
was  received  January  23,  1899. 

f  Cantor  Lectures  on  Mine  Surveying,  by  B.  H.  Brough,  London,  1892. 

|  A  Realise  on  Mine  Surveying,  by  B.  H.  Brough,  London  and  Philadelphia ; 
1st  edition,  1888  ;  7th  edition,  1899. 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS.  69 

under  the  title  of  Ein  wolgeordent  un  nutzlicTi  biiMin  wie  man 
Bergwerck  suchen  und  finden  soil.  The  wood-cut  of  the  miner's 
compass  there  published  shows  the  dial  divided  into  twice 
twelve  hours.  In  the  library  of  the  Freiberg  Mining  Academy 
there  are  copies  of  four  editions  of  this  rare  and  interesting 
book.  Of  the  edition  of  1505  only  two  or  three  copies  are 
known. 

A  compass  similar  to  that  found  at  Neudorf,  described  in 
the  paper,  is  exhibited  in  Florence.  It  belonged  to  Galileo. 

A  study  of  the  history  of  surveying-instruments  shows  that 
in  many  cases  inventions  have  been  anticipated  in  a  curious 
manner.  Thus,  the  ingenious  Rapid  Traverser,  invented  by 
Captain  Henderson  in  1892,  is,  I  find,  very  similar  to  an  instru- 
ment invented  by  Brigadier-General  James  Douglas,  and  de- 
scribed by  him  in  1727,  in  a  work  entitled  The  Surveyor's  Ut- 
most Desire  Fulfilled,  or  the  Art  of  Planometry,  Lorigim,etry  and 
Altimetry,  brought  to  its  greatest  Perfection  by  the  Help  of  the  Un- 
graduated  Instrument,  called  the  Infallible  (London :  Printed  for 
John  Osborne  and  Thomas  Longman  at  the  Ship  in  Pater- 
noster-row, MDCCXXVII.).  The  instrument  is  thus  described : 

"It  only  consists  of  two  Pieces,  viz.,  A  and  B,  whereof  A  is  a  square  Copper 
Plate,  with  two  moving  visual  Eulers  turning  round  upon  the  central  Screw  Nail 
D,  passing  through  the  Middle  of  the  Plate  A.  It  is  furnished  at  each  Corner  with 
a  thin  Piece  of  Brass,  which  may  be  taken  off  and  on  at  pleasure,  each  being 
pierced  to  receive  headless  Pins,  which  are  soldred  fast  to  the  Plate  ;  the  four 
Screws  are  to  make  their  Plates  hold  fast  the  Paper  when  properly  folded  at  the 
Corners  of  the  Instrument.  To  fit  the  Instrument  for  Use,  first  cover  the  Plate 
A  with  a  double  Sheet  of -clean  Paper.  Then  B,  your  Ball  and  Socket,  is  to  be 
joined  by  putting  the  Screw  Nail  thereof  through  the  central  Hole  of  the  Plate  A, 
gently  piercing  the  Paper  ;  which  done,  apply  the  two  visual  Bulers,  and  screw 
them  fast  with  the  middle  Screw  Nail  so  that  the  said  Kulers  move  easily  about 
the  centre :  and  thus  is  your  Infallible  prepared  for  Use." 

To  those  unacquainted  with  the  delicate  magnetic  instru- 
ments used  in  Sweden  for  discovering  iron-ores,  the  author's 
description  of  Thalen's  magnetometer  and  Tiberg's  inclination- 
balance  as  being  almost  identical  will  be  misleading.  These 
instruments,  which  should  hardly  be  classed  with  ordinary 
mine-surveying  instruments,  were  described  in  a  paper  on  ex- 
ploring for  iron-ore  with  the  magnetic  needle,  which  I  com- 
municated to  the  Iron  and  Steel  Institute  in  1887,  and  were 
admirably  illustrated  in  the  important  monograph  read  at  the 
Stockholm  meeting  of  that  Society  in  1898  by  Professor  G. 
Nordenstrom.  For  some  years  past  a  combination  of  the  two 


70  THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 

instruments  has  been  found  most  suitable  for  magnetic  explora- 
tions. 

Surely  Mr.  Scott  is  mistaken  in  ascribing  the  introduction 
of  the  instrument  shown  in  Fig.  14  to  W.  and  S.  Jones  in 
1796.  I  have  in  my  possession  a  graphometer  of  precisely 
similar  design,  made  at  Brunswick  in  1630 ;  and  graphometers 
of  even  earlier  date  are  exhibited  in  the  collection  of  astro- 
labes in  the  South  Kensington  Museum.  The  instrument  ap- 
pears to  have  been  invented  by  Jan  Pieterszoon  Dou,  of  Leyden, 
in  1612,  and  described  by  him  in  1620.  These  graphometers, 
being  made  prior  to  the  invention  of  the  vernier  in  1631,*  are 
of  interest  in  being  furnished  with  the  nonius,  or  variously  di- 
vided auxiliary  quadrants,  invented  by  Pedro  Nunez  in  1542. 

Referring  to  Mr.  Scott's  statement  that  a  diaphragm  and 
cross-hairs  in  the  focus  of  surveying-instruments  were  first  used 
in  1669,  I  may  point  out  that  Professor  E.  Hammer  has  shown 
that  this  was  first  done  about  the  year  1640,  in  England,  by 
William  Gascoigne,  who  fell,  in  1644,  at  the  age  of  twenty- 
four,  in  the  battle  of  Marston  Moor.  He  used  hair  and  thread 
for  this  purpose  thirty  years  before  Picard  and  Malvasia.  In 
the  middle  of  the  last  century  glass  and  mica  plates,  with  en- 
graved lines,  were  first  used  in  place  of  cross-hairs.  They  were 
described  by  Brander  in  1772,  and  were  used  by  Breithaupt  in 
1780.  Spiders'  webs  were  not  used  until  1775. 

Credit  for  the  first  application  of  the  tacheometric  principle 
in  surveying  is  given  by  the  author  to  "William  Green,  who  was 
awarded  a  premium  for  its  invention  by  the  Society  of  Arts  in 
1778.  This  view  I  adopted  in  a  paper  on  tacheometry,  com- 
municated to  the  Institution  of  Civil  Engineers  in  1888.  It 
has,  however,  recently  been  shown  by  Mr.  J.  L.  Van  Ornum, 
in  a  scholarly  memoir  published  by  the  University  of  Wiscon- 
sin, that,  although  in  1778  the  Danish  Academy  of  Sciences 
awarded  a  prize  to  G.  F.  Brander  for  a  similar  device,  which 
he  had  applied  to  his  plane-table  six  years  before,  its  real  dis- 
coverer was  James  Watt,  who  used  it  in  1771  for  measuring 
distances  in  the  surveys  for  the  Tarbert  and  Crinan  canals.  In 
James  Patrick  Muirhead's  life  of  James  Watt  is  found  a  state- 

*  The  vernier  was  invented  by  Capt.  Pierre  Vernier,  a  native  of  Burgundy, 
serving  the  King  of  Spain  in  the  Netherlands.  The  Germans  seem  to  have  used 
the  Teutonic  form  "  Werner."  See  Bauernfeind's  Elementeder  Vermessungskunde, 
7th  ed.,  Munich,  1889,  p.  124.— K.  W.  E. 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS.  71 

ment  by  Watt  himself  that  he  constructed  the  instrument  in 
1770,  and  that  in  1772  he  showed  it  to  Smeaton. 

It  is  interesting  to  compare  the  perfect  method  of  measuring 
lengths  by  means  of  the  American  steel  tapes,  referred  to  by 
the  author,  with  that  formerly  employed.  In  an  old  German 
work  on  surveying  by  Jacob  Koebel,  published  at  Frankfort 
in  1570,  the  unit  of  length  is  described  somewhat  as  follows : 
"  A  rood  should,  by  the  right  and  lawful  way,  and  in  accord- 
ance with  scientific  usage,  be  made  thus :  Sixteen  men,  short 
and  tall,  one  after  the  other,  as  they  come  out  of  church,  should 
place  each  a  shoe  in  one  line;  and  if  you  take  a  length  of 
exactly  16  of  these  shoes,  that  length  shall  be  a  true  rood." 
This  description  is  accompanied  by  a  quaint  illustration  show- 
ing the  process  being  put  in  operation.* 

MR.  SCOTT  :  Mr.  Newton  had  sent  me  an  electrotype  of  Hen- 
derson's Rapid  Traverser  to  accompany  the  text  in  my  article 
which  relates  to  it,  but  it  was  confiscated  by  our  Government 
officials  because  the  'importation  of  small  articles  of  merchan- 
dise through  the  mails  has  been  unjustly  prohibited  by  the  Uni- 
versal Postal  Union  Convention. 

I  cannot  let  Mr.  Brough's  description  of  the  "  Infallible  "  go 
by  without  citing  one  other  of  the  progenitors  of  Capt.  Hen- 
derson's Traverser,  to  which  Adams  has  made  casual  reference 
in  his  Essays,  the  first  edition  of  which  was  published  in  1791. 
He  says : 

"Mr.  Searle  contrived  a  plain  table,  whose  size  (which  renders  it  convenient, 
while  it  multiplies  every  error)  is  only  five  inches  square,  and  consists  of  two  parts, 
the  table  and  the  frame  ;  the  frame,  as  usual,  to  tighten  the  paper  observed  upon. 
In  the  center  of  the  table  is  a  screWj  on  which  the  index  sight  turns  ;  this  screw 
is  tightened  after  taking  an  observation." 

I  did  not  wish  to  convey  the  impression  that  Jones'  circum- 
ferentor  (Fig.  14)  was  unquestionably  the  first  of  its  kind  in 
England,  unless  what  Mr.  Newton  had  ventured  to  say  con- 
cerning it  would  tend  to  establish  that  fact.  Possibly  even  Mr. 
Newton  may  be  incorrect,  for  an  old  English  workf  has  this 
interesting  paragraph  : 

*  Geometrey  von  Kunstlichem  Feldmessen.  A  copy  of  this  rare  book  in  the  Astor 
Library,  New  York,  is  dated  1593.  The  edition  of  1570,  cited  by  Mr.  Brough,  is 
in  the  British  Museum.— E.  W.  K. 

f  Geodesia,  or  the  Art  of  Surveying,  John  Love,  London,  1744,  p.  59. 


72  THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 

"  This  last  instrument  depends  wholly  upon  the  Needle  for  taking  of  angles, 
which  often  proves  erroneous  ;  the  Needle  yearly  of  itself  varying  from  the  true 
North,  if  there  be  no  Iron  Mines  in  the  Earth,  or  other  Accident  to  draw  it  aside, 
which  in  mountainous  Lands  are  often  found  :  It  is  therefore  the  best  Way  for  the 
Surveyor,  where  he  possibly  can,  to  take  his  Angles  without  the  help  of  the  Needle, 
as  is  before  shewed  by  the  Semicircle.  But  in  all  Lands  it  cannot  be  done,  but  we 
must  sometimes  make  use  of  the  Needle,  without  exceeding  great  trouble,  as  in 
the  thick  woods  of  Jamaica,  Carolina,  &c.  It  is  good  therefore  to  have  an  Instru- 
ment with  which  an  Angle  in  the  Field  may  be  taken  either  with  or  without  the 
Needle,  as  is  the  Semicircle,  than  which  I  know  no  better  Instrument  for  the  Sur- 
veyor's Use  yet  made  publick." 

The  semicircle  Love  describes  had  fixed  and  movable  sights, 
though  divided  very  coarsely;  for  in  the  preface  of  his  work  he 


"  I  have  taken  Example  from  Mr.  Ho  well  to  make  the  table  of  Sines  and  Tan- 
gents but  to  every  fifth  minute,  that  being  nigh  enough  in  all  Sence  and  Reason 
for  the  Surveyor's  Use  ;  for  there  is  no  man,  with  the  best  instrument  that  was 
ever  made,  can  take  an  angle  in  the  Field  nigher,  if  so  nigh,  as  to  five  Minutes. >r 

I  have  recently  secured  a  copy  of  Prof.  Van  Ornum's  paper 
on  "  Topographical  Surveys,"*  and  am  glad  to  ascribe  to  Watt 
the  honor  that  seems  justly  due  him  in  having  been  first  to  use 
subtense  measurement  in  the  construction-work  on  the  Scottish 
canals.  I  had  found  a  record  of  this  fact,f  but  without  dates 
or  farther  detail. 

From  this  Bulletin  I  wish  also  to  supplement  my  remarks  on 
the  plane-table,  and  reproduce  here  the  description  and  cut  of 
the  original  instrument  (mentioned  on  p.  12),  for  the  benefit  of 
the  many  who  have  not  had  the  pleasure  of  reading  the  paper. 
Prof.  Van  Ornum  says,  in  part : 

"To  Johann  Prsetorius,  the  renowned  mathematician,  professor  and  savant, 
prolific  in  writings  and  inventor  of  many  mathematical  instruments,  is  definitely 
credited  the  invention  of  the  plane  table  in  1590.  To  enable  the  engineer  to  un- 
derstand the  famous  Praetorian  Mensula,  and  to  appreciate  its  peculiarities  and 
principles  of  construction,  Prof.  Carl  Dziatzko,  of  the  University  of  Gottingen, 
Germany,  has  sent  the  accompanying  cut  (Fig.  61)  and  description,  which  were 
taken  from  M.  Daniel  Schwenter's  Geometria  Practica,  Niirnberg,  1667.  A  B  C  D 
is  a  plane  board  about  15  inches  square  and  1  inch  thick,  having  two  cleats  on  the 
edges  to  prevent  it  from  warping.  In  the  corner  is  a  compass,  E,  in  a  square  box, 
having  a  sliding  lid,  so  that  it  can  be  opened  and  shut  at  pleasure.  A  spirit-level 
(not  shown)  is  necessary.  G  is  a  wooden  screw,  the  bottom  threaded,  and  the  top 

*  Bulletin  of  the  University  of  Wisconsin,  Engineering  Series,  vol.  1,  No.  10,  Dec., 
1896,  pp.  331-369. 

f  Inventors  and  Discoverers  in  Science  and  Useful  Arts,  John  Timbs,  F.S.A.,  N. 
Y.,  1860,  p.  287. 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 


73 


having  a  square  head.  There  is  a  nut,  H,  at  the  bottom.  In  the  center  of  the 
board  is  a  square  hole,  into  which  the  wooden  screw  G  is  glued.  K  I  is  a  hard- 
wood piece,  with  a  round  hole  at  I,  through  which  the  screw,  G  H,  passes.  To  K 
a  triangular  piece,  L,  is  nailed.  On  three  sides  of  this  piece  three  wooden  screws, 
M,  N,  O,  are  glued,  and  three  nuts,  P,  Q,  E,  made  for  them.  Three  pieces,  S,  T, 
V,  5  to  5£  feet  long,  are  made  to  fit  these  screws,  M,  N,  O,  thus  forming  the  tri- 

FIG.  61. 


The  Prsetorian  Mensula. 


pod.  A  graduated  brass  scale,  W,  14  inches  long  by  1  inch  wide,  forms  what  is 
called  the  chief  scale.  A  semicircular  piece  of  brass,  a,  is  left  at  one  end,  and  a 
hole  made  in  it  on  the  edge  of  the  rule  so  that  a  fine  needle  can  be  passed  through 
it.  Six  inches  from  this  a  similar  piece,  6,  is  left.  Two  sights,  e  and/,  are  made. 
The  sight  e  has  three  fine  holes  perpendicular  to  the  edge  of  the  scale  and  in  a 
plane  with  it.  The  sight/  has  a  hole  cut  in  it,  and  a  fine  wire  or  thread  stretched 


74 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 


across  it  in  the  plane  of  and  perpendicular  to  the  edge  of  the  scale.  These  sights 
are  made  so  that  they  can  be  turned  up  or  down.  Three  other  brass  rules,  X,  Y,  Z, 
similarly  graduated,  are  called  the  side  rules.  The  first  rule,  Z,  is  f  of  an  inch 
wide  and  1  foot  long,  and  is  fastened  rigidly  to  the  cleat  B  C,  so  that  the  edge  of 
it  is  in  the  middle  of  the  cleat.  The  second  rule,  Y,  is  similar  to  Z,  but  has,  be- 
sides, a  semicircular  piece  of  brass  fastened  to  one  end,  with  a  hole  in  it.  A  screw, 
g,  fits  in  this  hole  and  the  rule  is  fastened  to  the  cleat  B  C,-  so  that  it  coincides  with 
the  rule  Z.  This  rule  turns  about  the  screw  g,  and  has  two  sights,  the  same  as  the 
chief  rule.  The  third  rule,  X,  is  9  inches  long  and  is  soldered  to  a  square  piece 
of  brass,  so  that  when  it  is  fastened  to  the  table  it  will  be  perpendicular  to  the  rule 
Z.  The  point  where  the  top  edge  of  Z  crosses  this  rule  is  taken  as  the  zero  of  its 
scale.  A  rule,  n  i,  with  the  plumb-bob  k  attached,  is  used  for  centering  the  table 
over  a  point  in  the  field.  A  target,  q,  r,  s;  triangle,  /;  square,  t;  measuring  rod, 
p  ;  hammer,  m,  n,  o  ;  compass,  v ;  proportional  dividers,  x  ;  and  rule,  u,  complete 
the  secondary  equipment." 

Such  instruments  as  this  were  doubtless  the  first  to  be  used 
in  the   Swedish  mines;  and  where  I  have    said  (p.  13)  that 

they  were  rude  I 


FIG.  62. 


Plane  Table  Described  by  Simms. 


wish 

to  substitute  the  asser- 
tion that  they  were  very 
complete,  if  we  may 
judge  by  the  little  room 
there  has  been  found  for 
improvement  up  to  com- 
paratively recent  times. 
In  the  latter  part  of 
the  eighteenth  century 
Mr.  Beighton  had  used 
a  plane-table  with  a  tele- 
scopic alidade,  in  which 
the  telescope  was  placed 
at  one  end  and  a  coun- 


ter-weight at  the  other.  The  instrument  shown  in  Fig.  62,  which 
is  taken  from  a  standard  English  work,*  represents  the  construc- 
tion in  general  use  about  1840.  The  author  says  : 

"It  is  a  board,  A,  about  16  inches  square,  having  its  upper  edges  rabbeted  to 
receive  a  box-wood  frame,  B,  which  being  accurately  fitted  can  be  placed  on  the 
board  in  any  position  with  either  face  upwards.  This  frame  is  intended  both  to 
stretch  and  retain  the  drawing-paper  upon  the  board,  which  it  does  by  being  sim- 
ply pressed  down  into  its  place  upon  the  paper,  which  for  the  purpose  must  be  cut 
a  little  larger  than  the  board.  One  face  of  the  frame  is  divided  into  360°  from 


*  A  Treatise  on  Mathematical  Instruments,   F.  W.   Simms,  F.K.A.S.,  London, 
1834-1844. 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


FIG.  63. 


the  center,  C,  fixed  in  the  middle  of  the  board,  and  these  are  subdivided  each  way 
as  minutely  as  the  size  of  the  table  will  admit.  The  object  of  these  graduations 
is  to  make  the  plane  table  supply  the  place  of  the  theodolite,  and  an  instrument 
formerly  in  use  called  a  semicircle. 

"There  is  sometimes  a  second  center-piece,  D,  fixed  on  the  table  at  about  one- 
quarter  of  its  width,  from  one  of  the  sides  and  exactly  half  its  length  in  the  other 
direction. 

"  To  the  under  side  is  attached  a  center-support  with  ball-and-socket  or  parallel 
plate-screws,  by  which  it  can  be  placed  upon  a  staff-head,  and  made  to  sit  hori- 
zontal by  means  of  a  circular  spirit-level." 

The  author  says,  further,  that  the  box-wood  frame  and  its 
graduations  could  be  dispensed  with  entirely,  and  that  the  ex- 
pedition with  which  certain  field-work  may  be  performed  by  a 
person  who  is  expert  in  its  use  is  its  chief  recommendation. 

"W.  F.  STANLEY*  (communication  to  author) :  I  wish  to  ac- 
knowledge with  thanks  a  copy  of  your  article,  and  to  express 
my  pleasure  with  the  extent 
of  your  research.  In  the 
preparation  of  my  work  I 
spent  some  months  along 
these  lines,  but  only  par- 
tially succeeded;  therefore, 
I  know  the  trouble.  What 
you  have  said  concerning 
Fig.  40  I  believe  to  be  in- 
disputable facts,  but  I  beg 
leave  now  to  submit  a  des- 
cription of  an  instrument 
(Fig.  63)  which  I  completed 
in  the  latter  part  of  last  year 
(1898),  just  as  your  paper 
was  going  to  press.  It  is  the 
first  dial  of  the  Hedley  style, 
I  believe,  which  may  be  used  Stanle7's  Latest  Improved  Hedley-Dial. 
for  sighting  in  true  verticality.  The  Hedley  ring  did  not  per- 
mit this ;  but,  by  remodeling  into  a  sort  of  cradle,  this  diffi- 
culty is  avoided.  The  vertical  limb  is  now  a  complete  circle, 
and  graduated  to  read  on  the  upper  half  from  0°  to  90°,  in 
minutes  of  arc',  each  way.  In  the  lower  arm  of  its  vernier  is 


Math.  Instrument  Maker,  4  and  5  Gt.  Turnstile,  London,  England. 


76  THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

an  index,  which  is  used  to  indicate  the  correction  in  hypothe- 
nuse  and  base,  as  marked  on  the  lower  half  of  the  circle. 

The  horizontal  limh  is  graduated  outside,  as  shown,  and  reads 
to  minutes  by  double  opposite  verniers,  placed  so  as  to  be  -coin- 
cident with  the  line  of  sight. 

The  diaphragm  of  the  telescope  is  provided  with  platino- 
iridium  points  for  subtense  measurement,  as  described  in  my 
work,*  p.  128.  This  alloy  has  about  the  hardness  of  spring- 
tempered  steel,  and  is,  as  far  as  known,  perfectly  non-corrosive 
in  air  or  moisture.  We  have  found  that  this  point-reading  is 
more  exact  than  with  the  web,  as  irradiation,  due  to  the  edge- 
reading  of  the  web,  is  entirely  avoided. 

The  growing  sentiment  in  England  is  greatly  in  favor  of  3 
leveling-screws,  but  I  do  not  think  mine-surveying  so  exact  as 
surface,  and  the  strain  put  upon  the  axis  by  the  use  of  4  level- 
ing-screws  is  unimportant,  and  otherwise  much  minimized  by 
the  springiness  of  the  Hoffman-Harden  tripod  head.  The  great 
difficulty  with  our  engineers  here  is  to  get  head-room  in  the 
shallow  workings  of  our  coal-mines,  and  it  was  for  this  reason 
that  I  designed  the  prismatic  dial  you  have  illustrated  in 
Fig.  41. 

On  account  of  its  apparent  height  your  mine  tachymeter 
would  not  be  received  favorably  in  this  country.  The  dial  here 
described  has  been  built  as  low  as  the  conditions  will  permit, 
and  seems  to  answer  in  many  mines,  though,  as  I  say,  there  are 
obvious  reasons  why  it  should  be  still  lower.  Its  total  height, 
including  the  3J-inch  tripod  head,  is  10  inches,  and  it  weighs 
8J  pounds. 

MR.  SCOTT  :  The  height  of  my  instrument  is  not  so  great  as 
it  would  seem  by  a  casual  inspection  of  Fig.  56.  The  stand- 
ards are  purposely  made  a  little  higher  than  is  usual,  so  that, 
with  a  full  aperture  of  the  telescope,  it  can  be  made  to  observe 
objects  in  dips  up  to  about  55°,  and  as  great  as  63°  with  about 
one-quarter  of  the  diameter  of  the  objective  above  the  plates. 
They  are,  however,  no  higher  than  is  necessary  to  effect  conve- 
niently the  complete  revolution  of  the  9J-inch  main  telescope 
and  the  partial  revolution  with  the  5J-inch  auxiliary  telescope 

*  Surveying  and  Leveling  Instruments,  W.  F.  Stanley,  London,  2d  ed.,  1895. 


THE    EVOLUTION   OF    MINE-SURVEYING   INSTRUMENTS. 


77 


.FiG.  64. 


attached.  When  the  interchangeable  auxiliary  is  placed  on 
top,  the  total  height  from  the  tripod-head  in  the  5-inch  model 
is  14  inches,  and  the  total  weight  12  pounds,  or  5.5  kilo- 
grammes. 

C.  L.  BERGER  &  SONS*  (communication  to  author)  :  After 
much  difficulty  and  delay  we  have  been  enabled  to  secure  a 
photograph  of  the  nadir  instrument  (Fig.  64),  to  which  you 
have  referred  on  p.  701.  It 
was  designed  by  our  Mr.  C.  L. 
Berger  to  carry  the  alignment 
of  the  Dorchester  Bay  sewer 
very  accurately  down  through 
the  westernmost  of  the  three 
shafts  sunk  upon  it  in  driving 
its  entire  length  of  6090  feet. 
The  lower  part  of  the  cast-iron 
stand  rests  upon  three  supports, 
the  two  forward  being  con- 
trived to  act  as  leveling-screws, 
the  rear  one  being  merely  a 
stationary  swivel-point  upon 
which  the  upper  part  is  made 
to  move  slightly  in  azimuth  by 
means  of  the  opposing  tangent- 
screws  shown  acting  against 
two  small  pillars  near  the  base 
of  the  Y-standards. 

When  the  desired  position 
is  thus  attained,  the  base  is 
clamped  by  means  of  the  set- 
screws  or  nuts  shown  in  the 
forward  part  on  each  side.  The 
adjusting  block,  usually  set  into 
the  bearing  of  the  horizontal  axis,  was  dispensed  with  in  this 
case,  as  the  adjustment  could  be  secured  by  means  of  the  leveling- 
screws  and  a  delicate  striding-leyel  provided  for  that  purpose.' 

The  telescope  had  a  2-inch  aperture,  a  focal  length  of  about 


Nadir 


«"  Crafts  in 


*  Math.  Instrument  Makers,  Successors  to  Buff  &  Berger,  9  Province  Court, 
Boston,  Mass. 


78  THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

20  inches,  and  a  power  of  about  40  diameters.  As  in  all  tele- 
scopes of  this  length  and  size,  the  focusing  arrangement  is 
placed  at  the  ocular,  where  it  is  always  within  easy  reach. 

Mr.  Stearns,  in  the  paper  to  which  you  have  referred,  cor- 
rectly said :  "  As  the  use  of  a  vertical  cross-wire  would  have 
caused  confusion  on  account  of  its  looking  so  much  like  the 
string,  two  wires  crossing  each  other,  and  making  a  small 
angle  with  the  vertical,  were  used  instead." 

The  entire  weight  of  this  instrument  is  about  50  pounds. 

F.  W.  BREITHAUPT  &  SOHN*  (communication  to  author) :  We 
have  studied  very  carefully  the  copy  of  your  work  which  you 
sent  us.  We  regret  that  we  have  no  drawing  of  the  first  com- 
plete telescopic  mine-theodolite  made  by  us  in  1832  for  the  Im- 
perial Brazilian  Mining  Association  of  London. 

The  horizontal  circle,  however,  was  5  inches  in  diameter,  di- 
vided into  J°  and  read  by  verniers  to  1  minute  of  arc,  and  the 
ocular  provided  with  a  prism  for  steep  upward  sighting. 

We  send  you  a  copy  of  the  fourth  volume  of  our  Magazin, 
published  in  1860,  in  which  you  will  find  illustrated  a  mine- 
theodolite  (Fig.  65),  the  first  of  its  kind  in  Germany,  which  we 
made  for  the  Mine-Surveyor-General  of  Saarbriicken  in  1836, 
and  which  Bergingenieur  Praediger,  in  the  same  year,  used  in 
that  celebrated  survey  of  2000  meters  in  the  Ensdorfer  tunnel 
at  the  Kronprinz  coal-mines,  near  Saarlouis. 

It  will  interest  your  readers  to  notice  the  apparatus  provided 
to  measure  the  height  of  the  instrument  above  the  station  over 
which  it  is  set. 

It  was  made  of  five  small  tubes,  one  sliding  within  the  other, 
so  as  to  be  convenient  to  carry  about  and  quickly  attached  to 
the  hook  of  the  bar  that  passes  down  through  the  head  of  the 
tripod.  In  this  position  the  bottom  of  the  first  tube  was  always 
30  inches  below  the  horizontal  axis ;  the  next,  when  pulled  out 
its  full  length,  40;  the  next,  50,  etc.;  and,  finally,  the  odd 
inches  indicated  on  the  last  draw.  We  call  attention  also  to  the 
way  in  which  the  plummet  was  balanced  by  a  counter-weight — 
a  method  that  does  not  compare  very  favorably  with  the  reel- 
plummets  used  in  your  country  to-day.  The  tripods  had  exten- 

*  Math.  Instrument  Makers,  Established  1760,  Cassel,  Germany. 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS.  79 

FIG.  65. 


Praediger's  Original  Instrument  of  1836. 


80  THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 

sible  legs,  and  the  signal  targets  were  so  designed  that  their 
centers  should  correspond  with  the  axis  of  the  instrument  in 
height. 

FIG.  66. 


Breithaupt's  First  Eccentric  Mine- Theodolite. 

In  the  same  magazine  is  also  illustrated  the  eccentric  the- 
odolite (Fig.  66)  in  its  first  form,  as  it  appeared  in  1834. 
Among  the  advantages  claimed  for  it  then  may  be  enumer- 
ated : 

1.  It  may  be  used  to  sight  an  object  in  any  elevation  or  de- 
pression with  the  single  exception  where  the  object  is  exactly 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS.  81 

vertical  above  or  below  the  center  of  the  instrument,  and  this 
difficulty  can  be  obviated  by  a  little  shifting  of  the  object  or 
the  set-up  point.  As  a  little  disadvantage  one  could  mention, 
the  object  must  be  sighted  in  two  different  positions  of  the  tel- 
escope, unless  a  trigonometrical  calculation  is  made  to  account 
for  the  eccentricity  of  the  telescope ;  but  this  operation  is  not 
only  convenient  but  absolutely  necessary  to  compensate  for  the 
little  imperfections  in  instrumental  construction.  All  vertical 
angles  are  read  without  correction. 

2.  The  far  easier  adjustment  of  the  instrument. 

3.  Diminishing  the  height  of  the  telescope's  axis,  which  is 
only  2  inches  above  the  horizontal  plates. 

4.  Greater  length  of  telescopic  axis  between  its  supports  and 
larger  diameter  of  vertical  circle. 

5.  The  construction  is  such  that  the  bubble  tube  on  the  tele- 
scope can  also  be  placed  to  stride  the  axis  for  its  more  accurate 
adjustment. 

For  convenience,  the  telescope  had  a  prismatic  ocular,  and 
was  provided  with  a  reflector  to  measure  altitudes  of  the  sun,  for 
which  purpose  this  theodolite  is  well  adapted.  It  is  also  con- 
venient in  sighting  the  polar  star  to  establish  the  true  meridian. 
The  striding-compass  and  circular  box-bubble  are  both  on  top 
of  the  instrument,  and  very  easy  to  observe. 

We  cannot  give  any  authentic  information'  as  to  who  first 
used  this  instrument,  but  in  any  event  it  is  quite  wrong  that 
Borchers  had  used  it  as  early  as  1835,  as  you  record  it  on  p. 
27.  He  was  not  employed  at  Clausthal  until  1841.*  At  that 
time  he  found  there,  in  the  Royal  Mining  Academy,  a  theodo- 
lite of  our  make,  which  was  not  intended,  or  properly  designed, 
for  mine-surveying.  With  it,  however,  he  conducted  a  mine- 
survey,  the  results  of  which  were  so  satisfactory  that  he  was 
led  in  March,  1842,  to  order  a  theodolite,  which  we  delivered 
in  May,  1844.  We  regret  that  we  have  no  presentable  illus- 
tration ;  but  concerning  it,  we  will  say  that  the  vertical  circle 
was  divided  into  J°  and  read  by  opposite  verniers  to  minutes. 
The  horizontal  circle  was  6  inches  in  diameter,  divided  into  j-° 
on  silver  and  read  by  verniers  to  30".  The  vernier  openings 
in  the  covering  of  the  limb  were  provided  with  glass  plates  to 

*  See  Der  Bergiverksfreund,  vol.  xiv.,  p.  419. 


82  THE   EVOLUTION  OF   MINE-SURVEYING   INSTRUMENTS. 

protect  them  from  dust,  etc.,  the  invention  of  which  device 
must  be  credited  to  our  house  in  1835.  The  telescope  was  13 
inches  long,  was  reversible  upon  its  horizontal  axis  through 
the  standards,  and  provided  with  a  bubble-tube  that  could  be 
turned  to  the  line  of  sight.  There  was  also  a  striding-compass, 
but  the  special  feature  was  the  reflector  arrangement  fixed  to 
the  objective,  to  which  you  have  referred  on  p.  52  of  your  work. 
This  reflecting  mirror  moved  in  a  small  graduated  arc,  upon 
which  it  could  be  clamped  in  any  convenient  or  desirable  posi- 
tion, and  the  exact  value  of  the  deflection-angle  read  by  a  small 
vernier  provided  for  the  purpose. 

Borchers  had  this  concentric  instrument  in  commission  until 
1856.  On  June  10,  1850, 'the  great  Ernst- August  tunnel  was 
begun,  and  the  first  holing  was  made  in  1856.  Then,  on  ac- 
count of  the  work  to  be  done  in  inclined  shafts,  Borchers  had 
an  eccentric  theodolite  made  by  Meyerstein,  very  much  as  you 
have  shown  on  p.  26. 

PROF.  DR.  MAX  SCHMIDT*  (communication  to  author) :  As 
your  work  deals  only  incidentally  with  the  catageolabium  of 
F      67  Giuliani,  I  shall  be  glad  to  supplement 

it  at  your  solicitation  with  the  best  des- 
cription it  has  been  possible  for  me  to 
prepare  in  the  short  time  I  have  had  at 
my  disposal  for  this  purpose. 

On  p.  79,  Section  91  of  his  work, 
Giuliani  says : 

"  If  I  were  a  mine-surveyor  I  would  use  an  in- 
strument shown  in  Fig.  2,  Plate  V.  (here  repro- 
duced in  Fig.  67),  which  corresponds  in  its  prin- 
cipal parts  with  Brander's  Scheibeninstrument.  I 
will  call  it  Catageolabium^  as  it  serves  for  subterra- 
nean measurement." 


Here  follows    his    description,  from 
which  it  appears  that  the  circle  had  a 

Prof.  Giuliani's  Catageola-    Diameter  of  14  or  15  inches  and  was  di- 
vided into  24  hours  of  60  minutes  each. 
It  had  two  verniers,  by  which  the  hour-minutes  were  divided 

*  Vorstand  des  Geodetischen  Institute  der  Konigl.  Technischen  Hochschule,  Miin- 
chen,  Germany. 

t  Constructed  from  the  Greek  words  Kara,  downward  through,  yfj,  earth,  and 
Aa/3£iv,  to  take  or  to  measure. — SCOTT. 


THE    EVOLUTION   OF    MINE-SURVEYING   INSTRUMENTS. 


83 


into  15  parts.  On  the  alidade  there  was  a  small  circular  box- 
bubble  and  compass.  The  vertical  arc  was  of  6-inch  radius,  and 
provided  with  one  vernier,  by  which  each  degree  of  arc  could 
be  read  to  2  minutes.  Upon  this  vertical  arc  was  a  tube  sup- 
ported by  two  pillars  of  such  length  "  that  the  tube  can  see 
beyond  the  plate  in  very  precipitous  angles  "  (this  is,  therefore, 
certainly  the  first  top-telescope) ;  "  but  the  discomfort  experi- 
enced with  these  precipitous  angles  by  being  obliged  to  hold 
the  head  so  far  back  or  so  far  forward  over  the  plate  in  order 
to  get  the  eye  to  the  tube  is  avoided  by  unscrewing  the  front 
part  of  the  tube  and  substituting  another  small  tube  bent  at  a 

FIG.  68. 


One  of  the  Oldest-known  Broken-Telescopes. 

right  angle  and  provided  with  a  45°  reflector."     (This  is  the 
first  broken-telescope  that  I  know  of.) 

Another  very  old  broken-telescope  is  shown  in  the  accom- 
panying illustration  (Fig.  68).  It  is  one  made  by  an  unknown 
mechanic,  though  from  the  metal  work  and  workmanship  I 
should  say  that  it  came  from  the  shop  of  Hoeschel — the  son-in- 
law  of  Brander — somewhere  between  the  years  1800  and  1810. 
The  objective  is  achromatic  and  of  Fraunhofer's  design.  The 
instrument  consists  of  only  a  vertical  circle,  a  broken-telescope 
and  a  telescope-bubble  of  Brander's  pattern.  It  is  now  in  the 
possession  of  the  geodetic  department  of  the  Royal  Technical 
Academy  Hochsckule)  of  Munich. 


84 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


FIG.  69. 


Another  of  the  earliest  types  of  these  instruments  which  I 
have  in  my  collection  was  probably  made  by  Utzschneider  & 
Fraunhofer,  but  in  what  year  I  do  not  know.  The  striding- 
bubble  it  now  possesses  has  been  added  recently,  as  well  as  the 
micrometer-screws  and  verniers  of  the  vertical  circle.  But 
the  telescope,  the  horizontal  circle,  the  tripod  base  and  the 
arms  which  support  the  reading-glasses  remain  unchanged. 

.  I  send  also  another  illustration  (Fig.  69)  of  the  Scheibenin- 
strument  of  Hoeschel  as  modified  by  Oberbergrath  von  Yoith  in 
Amberg,  and  described  in  his  work.*  The  illustration  shows 

a  theodolite  of  Hoeschel  as 
it  was  duplicated  in  1792,  for 
the  Bavarian  Academy  of  Sci- 
ence, for  a  land-survey.  To 
adapt  this  theodolite  for  mine- 
surveys,  von  Yoith  (in  1805) 
replaced  the  telescope  with  a 
diopter-tube,  while  the  micro- 
meter-screws for  the  measure- 
ment of  angles  remained  un- 
changed. 

This  instrument  was  also 
provided  with  a  single  ver- 
nier at  one  end  of  an  alidade, 
or  arm,  at  the  opposite  end  of 
which  was  the  clamp  and 
tangent-screw.  For  mine-sur- 
veying there  were  provided 
signal-lamps,  in  which  the  rec- 
tangular window  was  marked 
with  a  cross.  Brander's  bub- 
ble-tube (which  was  hinged  at  one  end  and  provided  with 
double-adjusting  nuts  at  the  other)  occurs  again  on  the  vertical 
arc.  To  set  up  the  instrument  in  the  mine,  v.  Yoith  used  the 
Hungarian  surveying-buck. 

Komarzewski's  instrument  is  described  and  illustrated  in  the 
Journal  des  Mines,  No.  48,  Fructidor,  An  JTJ(1803).  Rapport  fait 

*  Vorschldge  zur  Vervollkommnung  der  Markscheiderinstrumente,  Ignaz  v.  Voith, 
Landshut,  1805. 


Von  Voith' s  Theodolite. 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS.  85 

a  rinstitut  National  des  Sciences  et  des  Arts  sur  un  Graphometre 
souterrain  destine  a  remplacer  la  boussole  dans  les  mines,  as  well  as 
in  the  little  work  entitled  Memoire  sur  un  Graphometre  souterrain 
(a  Paris  chez  Charles  Pong  ens),  which  says  that  the  instrument 
is  constructed  upon  the  same  principles  as  the  theodolite,  and 
consists  of  a  circular  disk,  which  is  placed  firmly  and  in  a  hori- 
zontal position  by  means  of  a  level  with  a  cylindrical  air- 
space. 

But  the  illustration  is  nothing  else  but  the  Msenscheibe,  a,s  it 
is  portrayed  in  von  Oppel,  and  as  it  was  improved  by  Studer  in 
Freiberg,  for  the  measurement  of  vertical  as  well  as  horizontal 
angles,  "  under  the  instructions  of  Krumpel,"  in  1792.*  Komar- 
zewski  made  surveys  in  the  mines  of  Freiberg  with  this  instru- 
ment between  1795  and  1801. 

Borchers,  while  a  mining  engineer  in  Clausthal,  wrotef  that 
in  France  mine-surveys  were  made  about  1835  with  a  the- 
odolite with  eccentric  telescope.  Reference  may  be  made  also 
to  an  article  by  Prof.  Combes,  Annales  des  Mines,  Series  3,  Tome 
ix.,  1836,  and  to  the  separate  edition,  published  in  the  same 
year,  and  entitled  Sur  les  leves  de  plans  souterrains,  etc. 

The  theodolite  as  a  mining-instrument  was  described  and 
illustrated  in  the  work  of  von  Hanstadt  in  1835;  but  in  the 
Bergwerksfreund,  vol.  14,  p.  392  (1851),  the  Royal  Prussian 
mine  surveyor  of  Saarbriieken  says  that  the  use  of  the  theodo- 
lite had  been  established  in  the  mines  there  since  1817.  The 
official  records  of  that  district  show  with  certainty  that 
Praediger  used  a  theodolite  there  in  1835.  Two  theodolites 
of  this  kind,  ordered  from  Breithaupt  by  the  Royal  Prussian 
Ministry  of  the  Interior,  were  described  by  Praediger  in  the 
JBergwerksfreund  in  1836. 

In  the  work  of  GensanneJ  is  described  the  Redpiangle  ou 
Graphometre,  which,  according  to  the  illustration,  consists  of 
a  half-circle  with  one  set  of  fixed  and  one  set  of  movable  sights, 
so  that  it  is  nothing  else  but  an  astrolabium.  Again,  the  work 
of  Duhamel§  describes  a  method  entitled  Lever  de  plan  d'une 
Mine  avec  le  Graphometre,  etc. 

*  Freiberger  gemeinnutzige  Nachrichteny  1803,  p.  189. 

f  Bergwerksfreund,  vol.  xiv.,  No.  40,  1851. 

J  Geometric  Souterrain^  M.  de  Gensanne,  Paris,  1770 ;  Montpellier,  1776. 

%  Geometric  Souterraine,  J.  P.  F.  G.  Duhamel,  Paris,  1787,  p.  179. 


8b  THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

The  solar  apparatus  shown  in  Fig.  54  was  first  made  in  Ger- 
many by  Hildebrand  of  Freiberg,  on  an  order  of  Bergingenieur 
Keller,  who  w^as  then  in  America,  but  with  improvements  sug- 
gested by  me.* 

MR.  SCOTT  :  Dr.  Schmidt  may  be  correct  in  ranking  Giuliani's 
instrument  as  the  first  of  broken-telescopes,  but  I  must  differ 
with  him  in  the  assertion  that  in  it  is  to  be  found  the  first  top- 
telescope  ;  for  while  the  sighting  tube  occupies  the  same  relative 
position  it  is  in  no  sense  an  auxiliary  device,  or  what  the  Ger- 
mans call  Hiilfsapparat.  There  is  a  distinction  between  an 
eccentric  main  telescope  and  an  eccentric  auxiliary  telescope, 
and  in  this  comparison  it  does  not  matter  whether  the  eccen- 
tricity occurs  at  the  side  or  above  the  center  of  the  instrument. 
The  sighting-tube  of  Giuliani's  instrument  is  no  more  to  be 
considered  a  /op-telescope  than  that  shown  in  Fig.  66  is  to  be 
considered  a  ^'de-telescope.  I  could  also  question  the  state- 
ment, but  not  with  the  same  degree  of  assurance,  that  the  sight- 
ing apparatus  in  the  Catageolabium  is  a  broken-telescope  at  all. 
It  seems  to  be  a  simple  application  of  a  prism  to  the  eye-piece. 
In  the  common  acceptation  of  the  term,  as  I  understand  it,  a 
broken-telescope  is  one  in  which  the  prism  is  placed  between 
the  ocular  and  the  objective,  as  I  have  it  in  Fig.  68.  There 
seems  to  be  a  prevailing  opinion  that  the  invention  of  the 
broken-telescope  belongs  to  Reichenbach.  T.  Ertel  &  Son,  his 
successors,  in  writing  to  me,  doubtless  with  reference  to  the 
instrument  mentioned  by  Prof.  Schmidt  (p.  84)  as  "  another 
of  the  earliest  types,"  say : 

"  Since  our  present  manager  came  to  the  direction  of  our  business  he  has  been 
able  to  discover  only  one  of  Reichenbach's  instruments,  which  we  sold  to  the  Royal 
Technological  Academy.  As  nearly  as  could  be  judged  by  its  appearance  it 
must  have  been  made  some  time  in  the  first  twenty  years  of  this  century,  but  we 
are  not  certain  that  this  was  the  first  of  its  kind." 

Illustrations  of  the  Eisenscheiben  of  von  Oppel,  to  which  Dr. 
Schmidt  has  referred,  I  reproduce  here  (Figs.  70  and  71)  from 
my  copy  of  this  justly  celebrated  old  work.f  On  pp.  207-212 
he  seems  to  say,  in  part : 

*  Zeitschr.  fur  Instrumentenkunde,  vol.  viii.,  p.  188. 

f  An leitung  zur  Markscheidekunst,  F.  W.  von  Oppel,  Oberberghauptmann  in  Dres- 
den, 1749. 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 


"I  divide  the  Eisenscheiben  into  two  principal  kinds,  those  that  give  the  angle 
in  the  common  degree  of  the  circle  and  those  which  express  it  in  hours,  etc.  The 
first  kind  (Fig.  70),  which  is  graduated  into  360°,  I  propose  to  make  as  follows: 
Take  a  circular  brass  plate  and  divide  it  into  four  quadrants,  each  of  which  is 
marked  with  a  Roman  numeral,  as  is  shown,  for  distinction.  Each  quadrant  is 
divided  into  degrees  and  numbered  each  way  from  the  principal  zero-line,  which 
is  engraved  upon  the  back  of  the  plate  as  well  as  upon  its  face.  The  index-arm 
must  now  be  pivoted  at  the  center  in  perfect  concentricity  with  the  plate,  and  at 
its  outer  extremity  provided  with  a  ring  or  hook,  to  which  the  measuring  chain 
may  be  conveniently  attached.  Then  make  a  stand,  the  base  of  which  can  be 
screwed  to  a  desired  station,  and  mount  the  plate  upon  it  by  two  hinges,  so  that  it 

FIG.  70. 


Von  Oppel's  Eisenscheibe,  Style  No.  1. 

can  revolve,  if  necessary,  to  a  horizontal  position  upon  the  90°-line.  If  the  small 
plummet  line,  which  is  attached  to  the  center  of  the  upper  part  of  the  base,  always 
coincides  with  the  meridian-line  that  is  engraved  upon  the  back,  the  base  will  be 
perfectly  horizontal. 

"The  Eisenscheibe,  which  is  divided  into  hours  (Fig.  71)  and  the  subdivisions 
thereof,  I  recommend  as  being  just  as  convenient  for  use.  In  a  solid  brass  circular 
plate,  which  is  hollowed  out  for  the  purpose,  is  inserted  a  smaller  graduated  disk, 
as  well  as  a  ring  surrounding  it,  each  of  which  may  be  revolved  about  a  common 
center  at  will  without  disturbing  the  position  of  the  other.  In  the  graduated  cir- 
cle the  cardinal  points  (Meridies,  Septentrio,  Occidens  and  Oriens)  are  marked  in 
reversed  position  as  in  the  compass,  and  upon  the  12th-hour  line  is  securely  fast- 


88 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


ened  a  strong  brass  plate,  standing  perpendicularly  upon  it,  and  holding  a  brass 
indicator-arm  provided  with  a  hook  at  its  outer  end,  to  which  the  brass  measuring- 
chain  may  be  attached.  The  intermediate  ring  is  divided  simply  into  quadrants, 
and  upon  its  meridian-line  are  two  small  blue  steel  pins  to  aid  in  moving  it  upon 
a  back-sight,  where  it  is  clamped  by  means  of  small  brass  pins  from  beneath. 
Through  the  outer  plate  are  bored  a  few  holes,  so  that  the  instrument  can  be 
securely  screwed  to  any  station-point.  On  each  side  of  the  vertical  plate  are  sus- 
pended small  plummets,  which  determine  the  horizontality  of  the  setting." 

FIG.  71. 


Von  Oppel's  Eisenscheibe,  Style  No.  2. 

D.  W.  BRUNTON,  Denver,  Colo,  (communication  to  the  Secre- 
tary) :  I  have  read  with  care  Mr.  Scott's  most  interesting  paper, 
and  regret  that  I  have  not  time  to  discuss  at  length  some  of  the 
many  questions  it  suggests. 

In  Aspen,  Leadville,  and  Red  Cliff,  Colo.,  and  generally  in 
western  mining  camps  where  contact  ore-bodies  occur,  and 
strip  or  vertical  veins  are  almost  unknown,  the  favorite  (and, 
to  my  mind,  by  all  odds  the  most  convenient)  instrument  is 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS.  89 

Buff  and  Berger's  new  high-standard  mountain  and  reconnois- 
sance  transit,  with  a  4-inch  horizontal  limb,  weighing  6  pounds. 
In  this  instrument  the  tangent-screws  are  placed  at  one  side, 
away  from  the  line  of  sight,  and  the  edge  of  the  horizontal  arc 
is  notched  as  deeply  as  possible  without  cutting  through  the 
metal.  This  arrangement,  combined  with  the  greater  elevation 
of  the  standards,  permits  angles  of  either  elevation  or  depression 
up  to  about. 70°  to  be  read  with  the  ordinary  telescope.  This 
is  as  far  as  it  is  ever  necessary  to  go  in  this  region,  except  on 
shaft-work,  which  is  always  done  by  plumbing.  The  great 
practical  objection  to  instruments  with  top  or  side  auxiliary 
telescopes  is  not  that  they  cannot  be  brought  into  adjustment, 
but  that,  being  elaborate  and  expensive,  they  must  be  carefully 

FIG.  72. 


Plan  of   Brunton's   Pocket-Transit  Opened   for  Taking  Courses  or  Horizontal 

Angles. 

kept,  and  therefore  are  frequently  in  the  office,  perhaps  several 
miles  away,  when  occasion  for  their  immediate  use  arises. 

At  the  request  of  the  Secretary,  I  take  pleasure  in  contribut- 
ing to  this  discussion  an  account  of  my  pocket  mine-transit,* 
manufactured  by  William  Ainsworth  &  Son,  Denver,  Colo., 
and  already  in  use  in  every  country  from  Australia  to  Alaska. 
It  is  employed  in  the  work  of  the  United  States  Geological 
Survey,  and  the  surveys  of  most  of  the  States  and  of  Canada. 
Instruction  in  the  use  of  it  is  a  part  of  the  engineering  course  at 
the  Lawrence  Scientific  School,  Harvard  University,  the  School 
of  Mines,  Columbia  University,  and  a  number  of  the  western 
mining  schools.  The  chief  merits  of  this  instrument  consist  in 

*  Patented  September  18,  1894. 


90 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


FlG.  73. 


its  extreme  portability  and  the  extraordinary  rapidity  with  which 
reasonably  accurate  surveying  can  be  performed  by  its  use. 

Many  years  ago  I  began  experimenting  with  the  purpose  of 
devising  a  combination-instrument  which  would  perform  all 
the  necessary  survey-work  required  for  current  daily  mining 
practice  and  commercial  and  legal  mine-examinations.  After 
constructing  six  or  eight  different  forms,  I  hit  upon  the  design 
now  finally  adopted,  and  made  arrangements  for  its  manufac- 
ture with  the  house  above  named.  The  development  and  in- 
troduction of  this  instrument  has  been  with  me  a  labor  of  love, 
and  not  an  enterprise  looking  to  commercial  profit ;  and  the 
same  is,  to  a  considerable  degree,  true  of  the  manufacturers, 
who  'use  the  utmost  care  in  the  produc- 
tion of  the  instrument,  and  push  its  sale 
largely  as  an  indirect  advertisement  of 
their  chief  business,  namely,  the  manu- 
facture of  instruments  of  precision  and 
high-class  balances,  in  which  latter  line 
they  have  already  surpassed  nearly  all 
competitors,  and  achieved  the  command 
of  the  American  market. 

The  dimensions  of  this  pocket-transit 
are    2|-    by  2|-    by  -^|-  inches,   and   the 
weight  (in  aluminum  case)  is  8  ounces. 
In  other  words,  it  is  strictly  a  pocket-in- 
strument, and  is,  in  fact,  carried  in  the 
pocket  like  an  ordinary  compass,  which 
I     it  does  not  exceed  in  bulk.     Yet  it  does 
Correct  Position  in  Taking  the  work  of  a  sighting-compass,  a  clinom- 
Courses  or  Horizontal  An-    t         prismatic  compass,  and  an  Abney 

gles  not   more  than   45°  * 

above  or  15°  below  the  or  -Locke  level,  measuring  horizontal  and 
Observer.  vertical  angles,  dips,  etc.,  with  a  high 

degree  of  accuracy. 

I  will  not  enter  into  detail  here  as  to  the  manner  of  its  use 
for  all  these  purposes.  The  manufacturers  will  furnish  on 
demand  a  circular  covering  these  particulars,  and  a  few  gen- 
eral remarks  will  be  sufficient  in  this  place. 

Fig.  72  is  a  plan  of  the  transit  when  opened  for  taking  courses 
or  horizontal  angles.  It  shows  a  spirit-level,  which  should 
be  set,  for  this  operation,  at  right-angles  to  the  line  of  sight. 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS.  91 

Fig.  73  shows  the  proper  method  of  holding  the  instrument 
in  taking  courses  and  horizontal  angles. 

The  instrument  is  correctly  sighted  on  the  object  when  the 
eye,  looking  into  the  mirror  which  lines  the  lid,  sees  the  black 
center-line  bisecting  both  the  opening  in  the  front  sight  and 
the  object  sighted  at;  after  which,  the  reading  of  the  needle  is 
comparatively  easy  if  the  proper  precautions  as  to  position  and 
leveling  have  been  observed.  The  most  important  of  these  is, 
that  the  instrument  should  not  be  turned  in  the  hands,  as  is 
customary  with  an  ordinary  compass,  but  the  hands  should  be 
held  rigidly  against  the  body,  which  should  serve  as  a  tripod 
for  the  instrument,  and  changes  of  direction  should  be  made 
by  twisting  the  body  to  right  or  left,  preserving  the  level  posi- 
tion as  indicated  by  the  bubble. 

For  inclined  sights  and  for  taking  dips,  the  bubble-tube 
(which  is  easily  revolved,  by  means  of  a  crank  on  the  back  of 
the  instrument,  with  the  middle  finger  of  the  right  hand,  while 
the  thumb  and  fore-finger  grasp  the  instrument)  furnishes  an 
accurate  reading  by  means  of  the  vernier  attached  to  it  (Fig. 
72)  and  revolving  with  it. 

A  little  practice  will  enable  the  engineer  to  perform  with 
this  small  pocket-transit  work  of  great  variety  and  surprising 
accuracy  at  very  little  cost  of  time.  In  many  cases,  such  a 
small  and  portable  instrument  will  be  to  the  engineer  a  most 
agreeable  change  from  the  numerous  old-fashioned  contri- 
vances which  it  supplants. 

H.  D.  HOSKOLD,  Buenos  Aires,  Argentine  Republic,  S.  A.* 
(communication  to  the  Secretary) :  The  writer  is  not  aware  that 
any  record  exists  indicating  the  period  when  angular  and  linear 
measurements  were  first  introduced  and  practiced  as  a  science, 
and  the  form  of  the  instruments  employed  as  auxiliaries  in 
useful  astronomical  observations  and  engineering  operations 
for  scientific  and  economic  purposes.  Still,  as  previously  stated, f 
he  believes  that  the  first  instruments  were  exceedingly  rude  in 
construction,  and  probably  consisted  for  the  most  part  of  two 

*  Director  of  the  National  Department  of  Mines  and  Geology  and  Inspector 
General  of  Mines  of  the  Argentine  Republic.  This  communication  was  received 
May  5,  1899. 

f  Trans.  Am.  Soc.  Civ.  E.,  vol.  xxx.,  p.  137,  1893. 


92  THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

movable  cross-bars  of  wood  or  metal  fixed  on  the  top  of  a  rod, 
the  opposite  end  of  which  was  thrust  into  the  ground  for  use ; 
or  some  such  contrivance  may  have  been  placed  on  a  square 
board  in  the  form  of  a  plane-table.  The  angles  observed  and 
formed  by  the  radial  bars  may  also  have  been  determined  in 
linear  measure  by  applying  a  simple  straight-line  divided  scale 
of  equal  parts,  similar  in  principle  to  that  which  was  applied 
to  the  cross-staff  of  navigators  in  1514,*  or  by  the  divided  sides 
of  a  quadrilateral  figure  or  geometrical  square  described  upon 
a  board. 

Nevertheless,  in  the  Chaldean  records,  recently  discovered, 
mention  is  made  of  an  iron  wheel  (or  circle)  constructed  some 
4000  or  4500  B.C.  ;  but  nothing  is  said  about  its  use.  It  is  im- 
portant to  note  that  the  late  Mr.  George  Smith,  of  the  British 
Museum,  discovered,  prior  to  1870,  in  the  ruins  of  the  tile- 
brick  library  in  the  Palace  of  Sennacherib  (704  B.C.),  a  large 
fragment  of  a  circular  Assyrian  astrolabe,  the  circumference 
being  originally  divided  into  12  equal  parts,  corresponding  to 
the  signs  of  the  zodiac  and  months  of  the  year.  It  had,  also, 
an  inner  circle,  and  in  each  division  the  principal  or  prominent 
stars  are  found.  This  instrument  is  at  least  2604  years  old, 
and  probably  the  oldest  on  record. 

The  ancient  astronomers  (date  unknown)  employed  copper 
circles  of  large  diameter  placed  in  the  meridian,  as  also  at  right 
angles  to  that  line ;  f  but  we  have  no  evidence  how  they  were 
divided.  Astronomical  and  other  observations  were  practiced, 
it  is  said,  in  Egypt  3000  B.C.  ;  as  they  were  also  in  China  2700 
B.C.,  if  Chinese  history  is  worthy  of  credence.  A  Chinese 
emperor,  Hwang-ti,  is  said  to  have  invented  the  cycle  of  60 
years,  2600  B.c.J  He  has  also  been  credited  with  the  invention 
of  various  astronomical  instruments,  including  one  for  observ- 
ing the  four  cardinal  points,  which  is  generally  considered  to 
have  been  a  magnetic  compass ;  §  but  it  was  more  probably  a 
circumferentor.  It  is  recorded  that  early  Buddhist  astronomy 
possessed  instruments  made  of  brass ;  but  their  inferiority  and 
mode  of  use  caused  them  to  give  place  to  larger  ones,  enormous 

*  Life  of  the  Navigator  John  Dams  (1578),  p.  145,  1889. 

f  J.  S.  Bailly,  Histoire  de  V  Astronomic  Ancienne,  2d  ed.,  1781,  p.  13. 

J  Davis,  History  of  China,  vol.  i.,  p.  219,  1857. 

\  J.  S.  Bailly,  op.  cit.,  p.  121. 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS.  93 

instruments  built  up  of  masonry,  the  divided  portion,  or  arc 
of  the  circle,  being  of  marble.  With  these  instruments,  angles 
were  measured  to  single  minutes.  In  1729  such  an  instrument 
existed  in  Delhi,  and  a  degree  upon  its  divided  limb  was 
measured  equal  to  2-|  inches.  Claudius  Ptolemy,  in  the  second 
century,  possessed  similar  instruments,  as  also  the  astrolabe, 
with  four  circles  placed  in  different  planes,  which  had  been 
invented,  some  300  years  before,  by  Hipparchus,  the  greatest 
discoverer  in  mathematics,  astronomy,  geography,  etc.,  of  an- 
cient times. 

From  what  has  been  brought  forward,  it  cannot  be  fairly 
argued  that  the  ancients  may  not  have  possessed  portable  cir- 
cular instruments  for  rough  land-observations  long  prior  to  the 
times  of  Hipparchus,  Ptolemy  or  Sennacherib.  Unfortunately, 
however,  the  infamous  and  ever-to-be-lamented  destruction  of 
the  Alexandrian  libraries,  an  incalculable  loss  to  the  world  for 
all  time,  has  placed  it  out  of  our  power  to  determine  the  par- 
ticular form,  nature  and  size  of  the  instruments  used  during  the 
earlier  ages.  The  sculptured  and  painted  figures  recently  dis- 
covered upon  the  walls  of  a  copper-mine  at  Wady  Magerah, 
which  was  worked  under  the  reign  of  the  Egyptian  King  Sene- 
fura,  4000  B.C.,  and  also  the  map  of  an  Egyptian  gold-mine  from 
1400  to  1600  B.C.,  afford  strong  inferential  evidence  that  mine- 
surveying  was  known  and  practiced  at  a  very  early  period  of 
the  world's  history.  From  that  period  to  the  time  of  Hero 
and  Euclid — also  improvers  of  instruments  and  the  science  of 
surveying — little  of  importance  is  known  relative  to  such  mat- 
ters ;  neither  have  particular  details  come  down  to  us  regard- 
ing the  instruments  and  mode  of  surveying  adopted  during 
the  earlier  Greek  and  Roman  mining  period.  Even  the  great 
Roman  engineer,  Antoninus,  does  not  appear  to  have  employed 
any  angular  instrument  in  determining  the  direction  of  the 
various  lines  of  roads  measured  by  him  in  the  nations  con- 
quered by  the  Romans.  It  is  highly  probable  that  mine-sur- 
veying was  forgotten  more  or  less,  or  hid  in  obscurity  for 
several  centuries,  as  a  forbidden  art,  or  suspicious  dark  practice. 

Tradition  affirms  that  the  first  mode  of  performing  surveys 
in  mines  in  England  involved  the  use  of  a  low,  three-legged 
stool,  like  a  small  plane-table,  a  chalked  string,  some  kind  of 
measure,  and  a  book  for  entries.  It  seems  that  the  plane-table 


94  THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

was  fixed  at  the  end  of  the  first  bend  in  the  underground  road, 
and  the  string,  held  in  the  direction  of  the  road  leading  back 
to  the  shaft,  was  then  raised  a  little  by  the  forefinger  and  thumb, 
and  let  fall  suddenly,  producing  upon  the  table  a  chalk-line,  a 
portion  of  which  was  erased  to  leave  room  for  succeeding  lines. 
The  string  was  then  stretched  in  a  forward  direction  and 
treated  as  before,  the  measure  of  the  lines  being  entered  in  a 
book,  as  also  the  number  of  the  chalk-lines.  At  the  second 
bend  in  the  road  the  last  preceding  forward  line  was  brought 
into  the  direction  of  the  last  piece  of  road  measured,  and  the 
string  stretched  in  a  forward  direction.  Thus  a  kind  of  rough 
traverse-plotting  was  carried  on  underground.  Undoubtedly, 
however,  that  plan  of  surveying  must  have  been  limited  to  a 
few  lines.  It  is  also  probable  that  such  surveys  were  made 
with  the  purpose  of  repeating  them  at  the  surface ;  and,  if  so, 
the  direction  of  the  first  line  in  the  underground  working 
must  have  been  determined  by  suspending  two  lines  down  the 
shafts,  which,  in  those  early  times,  were  very  shallow.  When 
the  writer  was  a  boy  he  heard  an  old  miner  of  eighty-four 
make  this  statement,  and  the  old  man  had  heard  it  from  his 
grandfather.  Whether  this  plan  of  surveying  is  older  than 
Agricola,  1546 ;  Digges,  1571 ;  or  Houghton,  1681,  cannot  be 
determined ;  but  it  is  highly  probable  that  it  preceded  the  latter, 
and  continued  to  be  employed  after  he  wrote  his  work  on  Sur- 
veying of  Mines.  This  mode  of  the  three-legged  stool  may 
also  have  given  rise  to  the  old-fashioned  land-surveying  plane- 
table. 

It  is  on  record  that  the  "  good  ship  Plenty  "  sailed  from  Hull 
in  1338,  directed  by  the  mariner's  or  sailing  (magnetic)  needle; 
so  that  a  rough  magnetic  compass  could  have  been  employed 
in  England  for  mining  and  other  surveys  previous  to  the  time 
when  Agricola  wrote ;  but  there  does  not  seem  to  be  any  actual 
proof  that  such  was  the  case  during  the  long  interval  which 
elapsed  until  the  time  of  Houghton. 

Quadrants  and  plane  circular  astrolabes,  the  one  divided  into 
90°  and  half  of  the  other  sometimes  to  180°,  for  measuring  the 
elevation  of  the  sun  and  stars  at  sea  and  on  land,  existed  at  an 
early  period  in  the  East,  in  Spain,  and  in  England.  The  former 
had  plain  sights  attached  to  one  side,  with  a  plumb-line  to  mark 
the  angle.  The  circular  instruments  had  plain  sights  attached 


THE    EVOLUTION   OF    MINE-SURVEYING   INSTRUMENTS.  95 

to  a  radial  bar,  revolving  around  the  circumference  in  the  same 
manner  as  in  Digges's  theodelitus.  Such  quadrants  and  astro- 
labes were  sometimes  suspended  by  a  ring  in  the  vertical  plane 
of  the  object  to  be  observed.  Two  such  instruments  as  those 
described,  of  small  diameter,  are  represented  upon  the  second 
original  Borgian  Map  of  the  World,  by  Diego  Bibero,  Seville, 
1529,  which  map  is  preserved  in  good  condition  in  the  museum 
of  the  Propaganda  at  Rome.  The  instruments  referred  to 
are  divided  to  single  degrees,  and,  in  that  respect,  are  supe- 
rior to  the  theodelitus  of  Digges ;  the  parts  of  a  degree  were  esti- 
mated. An  exceedingly  curious  ancient  magnetic  compass, 
with  five  divided  circles,  is  also  engraved  upon  that  map.  The 
instruments  of  Ribero  were  of  a  common  type,  used  long  be- 
fore and  after  his  time,  and  they  present  sufficient  evidence  to 
prove  that  these  were  the  models  from  which  the  compass  of 
Agricola,  1546,  and  Digges,  1571,  and  others  were  derived. 
The  astrolabe,  in  fact,  in  its  simplest  form  was  a  plane  circle 
(in  contradistinction  to  that  with  four  circles  in  different  planes, 
sometimes  divided  half-way  round,  and  sometimes  entirely  so), 
and,  consequently,  must  have  been  used  for  land-surveying  ex- 
actly in  the  manner  described  by  Digges.  At  the  International 
Geographical  Congress,  London,  1896,  the  authorities  of  the 
British  Museum  exhibited  a  number  of  astrolabes — the  earliest 
being  one  made  in  Toledo,  Spain,  in  1067.  There  were  also 
one  made  in  Valencia  in  1086 — evidently  derived  from  Moorish 
or  Arabian  sources — and  one  made  in  Cairo,  1240,  as  well  as 
one  made  of  brass,  in  England,  in  1260,  and  one  formerly 
belonging  to  Sir  Francis  Drake,  1570,  besides  various  others 
of  the  fourteenth  century  and  succeeding  dates. 

With  the  exception  of  the  omission  of  some  types  of  survey- 
ing instruments,  Mr.  Scott  has  fairly  represented  in  his  paper 
the  progress  made  in  various  countries  in  the  construction  of 
instruments  for  the  object  under  discussion.  In  the  copy  of 
Digges's  second  edition,  1791,  in  the  possession  of  the  writer, 
Chapter  27,  there  is  a  diagram  of  his  2-foot  surveying  circle — 
theodelitus — a  copy  of  which  was  sent  to  Mr.  Scott.  We  cannot 
suppose,  however,  that  a  circle  of  so  large  a  diameter  was 
commonly  used  in  mines;  still,  it  could  have  been  so  em- 
ployed. Nothing  would  be  gained  by  following  Mr.  Scott  in 
detail,  because  he  has  done  his  work  so  well. 


96  THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

It  would  appear,  however,  that  little  improvement  was  made 
in  land-  and  underground-surveying  instruments  up  to  the 
time  when  Ramsden.  completed,  about  1760,  the  grand  inven- 
tion which  he  applied  in  practice  during  the  period  from  1784 
to  1799.  Others  followed,  some  time  prior  to  1788,  in  Ger- 
many, and  also  probably  in  France  about  1790.  As  far  back 
as  1804,  Fenwick,  a  celebrated  surveyor  and  colliery  viewer  of 
Durham,  England,  proposed  the  plan  of  a  "  fast  needle,"  as  he 
termed  the  circumferentor  or  rough  theodolite-limb,  constructed 
in  his  time.  Still,  he  had  to  depend  upon  the  magnetic  needle 
to  obtain  the  bearing  of  some  selected  line  in  the  survey. 
Fenwick's  book  contains  a  complete  system  of  magnetic-com- 
pass or  dial  surveying,  and,  so  far  as  that  system  is  concerned, 
it  has  not  been,  nor  will  it  ever  be,  superseded. 

Various  opinions  had  been  emitted  from  Fenwick's  time  up 
to  1842,  when  Butler  Williams,*  a  prominent  English  civil  en- 
gineer, suggested  the  necessity  of  improving  the  theodolite  and 
adapting  it  more  generally  to  mine-surveys.  He  also  wrote  a 
very  concise  and  exceedingly  useful  chapter  upon  underground 
surveying,  suggesting  the  use  of  three  tripods,  as  also  a  system 
of  plotting  underground  surveys  by  co-ordinates.  Combes 
and  D'Aubuisson  had  formerly  attempted  to  introduce  some 
such  plan ;  still,  such  was  the  opposition  and  obtuseness  of  that 
period,  that  the  miners'  dial  in  some  form  or  another  was,  and 
still  is,  continued  in  use  for  mine-surveying.  Various  authori- 
ties have  stated  that  the  writer  was  the  first  in  England  to 
publish,  in  1863,  a  general  system  of  mine-surveying  by  the 
sole  use  of  the  theodolite.  That  work  advocated  plotting  un- 
derground surveys  by  the  co-ordinate  system,  and  for  this  and 
other  useful  purposes  a  complete  set  of  traverse-tables  formed 
part  of  the  work  alluded  to.f 

Although  no  account  of  the  miners'  transit-theodolite  (Fig. 
74)  was  published  earlier  than  1863,  still  the  writer  believes  that 
he  had  it  in  use  prior  to  1858.  By  means  of  a  long  diagonal 
eye-piece,  the  instrument  was  intended  to  be  used  for  con- 
necting underground  workings  to  the  surface  by  direct  sight- 
ing up  a  shaft,  and  fixing  an  illuminated  wire  in  the  same  direc- 

*  Practical  Geodesy,  B.  Williams,  C.  E.,  pp.  207,  219,  1842. 

t  Practical  Treatise  on  Mining,  Land  and  Railway  Surveying  and  Engineering,  Lon- 
don, 1863. 


THE    EVOLUTION   OF    MINE-SURVEYING   INSTRUMENTS.  97 


FIG.  7.4. 


HOSKOLD'S  MINERS-  TRANSIT  THEODOLITE/^ 

In     tl.e  right-lard  lower  corner  is  shown  the  method  of  mounting  upon  three 

leveling-screws. 


98  THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS. 

tion  as  the  first  drift  underground.  In  deep  and  wet  shafts 
this  plan  was  impracticable ;  but  in  shallow  dry  pits,  when  the 
operation  was  performed  on  dark  nights,  fair  success  was  ob- 
tained. For  deep  pits,  the  writer  found  that  two  chains  made 
in  a  particular  form  of  steel  wire  of  different  sizes,  to  support 
the  weight  suspended  down  a  shaft  for  determining  the  direc- 
tion of  the  first  line  in  the  underground  survey,  were  com- 
pletely satisfactory. 

The  theodolite,  Fig.  75,  was  designed  soon  after  that  repre- 
sented by  Fig.  74 ;  but  it  was  not  constructed  until  about  1862- 
63,  and  an  account  of  it  wTas  published  in  1865.*  However, 
some  defects  had  been  introduced  in  the  construction,  and 
being  pressed  for  time,  the  writer  did  not  attend  further  to  the 
matter  until  1889,  when  Troughton  &  Simms  made  some  alter- 
ation in  the  instrument,  making  it  as  represented  in  Plates  I. 
and  II.  of  the  writer's  paper,  published  in  1893.f  That  firm 
also  constructed  a  new  instrument  of  the  same  class  as  that 
under  consideration,  introducing  some  improvements  repre- 
sented in  Fig.  75,  which  was  exhibited  in  the  Argentine  Mining 
and  Metallurgical  Section  at  the  Chicago  Exhibition  in  1893. 
The  jury  on  scientific  instruments  gave  the  highest  award  for 
the  instrument,  finding  the  chief  points  of  excellence  in  it  to 
be  as  follows : 

"  1.  It  is  an  instrument  of  new  appliances. 
"2.  Peculiarity,  beauty  and  novelty  of  construction. 

"3.  Adapted  to  facilitate  surveying  operations  with  greater  accuracy  and  in 
less  time  than  is  usual  with  surveying  instruments. 
"4.  It  is  a  general  labor  and  time  saver." 

As  may  be  seen  in  Fig.  75,  one  of  the  principal  improvements 
consists  in  the  adaptation  of  a  second,  or,  as  we  should  term  it, 
lower  telescope,  arranged  to  move  upon  a  short  horizontal  axis, 
the  telescope  occupying  an  elongated  or  oval-shaped  opening 
made  in  the  center  of  the  enlarged  part  of  the  lower  vertical 
axis.  Each  end  of  the  short  horizontal  axis  is  suspended  in  a 
collar  between  four  adjusting  screws,  which  pass  through  the 
termination  of  a  short  horizontal  cylinder,  the  collar  of  which 
is  firmly  screwed  or  cast  to  the  outside  of  the  lower  vertical 

*  Trans.  S.  Wales  Mining  Engineers,  vol.  iv.,  No.  5,  1865. 
f  Trans.  Am.  Soc.  Civ.  E.,  vol.  xxx.,  pp.  135-154,  1893. 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS.  99 

FIG.  75- 


HOSKOLD-S  ENGINEERS'  THEODOLITE  > 


100          THE    EVOLUTION   OF    MINE-SURVEYING    INSTRUMENTS. 

axis.  The  telescope  is  thus  secured  against  lateral  vibration, 
and,  by  the  two  sets  of  screws  named,  may  be  adjusted  to  coin- 
cide with  the  optical  axis  of  the  upper  telescope  when  the  zero 
of  the  verniers  coincides  with  360°,  90°  and  180°.  It  moves 
vertically  a  few  degrees,  sufficient  for  sighting  elevated  or  de- 
pressed objects  within  its  range,  upon  the  surface.  For  use 
underground,  when  elevated  or  depressed  stations  are  beyond 
the  vertical  range  of  the  telescope,  a  reflector  applied  to  the 
object-end  of  the  lower  telescope  reflects  any  object  situated 
in  the  perpendicular  or  vertical ;  or  the  upper  telescope  may 
be  used  instead.  By  an  ingenious  contrivance  of  the  maker, 
this  reflector  may  be  attached  or  detached  at  pleasure,  and, 
when  attached,  its  lateral  plane  or  reflecting-surface  is  at  right- 
angles  to  the  optical  axis  of  the  telescope. 

The  upper  telescope  is  mounted  on  Y's  sufficiently  high  to 
give  the  amount  of  vertical  angle  which  may  be  required  in 
any  class  of  mine ;  and  its  horizontal  axis  carries  a  divided 
semicircle  on  each  side  of  the  telescope,  giving  a  perfect  bal- 
ance to  the  upper  parts  of  the  theodolite,  without  employing 
useless  dead  counterpoise  weights.  A  groove  about  three-quar- 
ters of  an  inch  in  width  and  four  inches  in  length  is  fixed 
upon  the  upper  telescope,  into  which  a  corresponding  part  of  a 
large  circular,  as  also  a  long-trough,  magnetic  compass  may  be 
slid  for  use  underground  or  upon  the  surface,  independently  of, 
or  in  connection  with,  the  readings  of  the  theodolite-limb.  The 
circular  compass  carries  a  long  sensitive  needle  with  a  vernier 
at  each  end,  which  may  be  made  to  read  either  to  single  minutes 
or  to  20  seconds,  as  may  be  required.  The  horizontal  axis  of 
the  upper  telescope  is  perforated  to  admit  the  rays  of  light 
from  a  lantern  to  illuminate  the  hairs  underground ;  or,  for 
night-work,  a  reflector  is  also  attached  to  the  lower  telescope. 
A  sensitive  stride,  or  axis-level  is  provided  also. 

A  special  form  of  micrometrical  eye-piece,  not  shown  in  Fig. 
75,  is  attached  to  the  telescope  when  required,  and  may  be  made 
to  read  to  single  seconds.  Its  chief  use  is  the  determination  of 
distances  by  the  sub-tense  system,*  which,  in  the  opinion  of  the 
writer,  is  much  superior  to  the  stadia  plan.  This  micrometrical 
apparatus  may  also  be  used  as  an  auxiliary  to  the  readings 
obtainable  from  the  verniers  of  the  theodolite. 

*  Trans.  Am.  Soc.  Civ.  E.,  vol.  xxx.,  pp.  147,  148. 


THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS.         101 

The  simple  but  efficient  arrangement  of  two  telescopes  in  the 
instrument  under  notice  enables  an  observer  to  dispense  with 
the  usual  practice  of  making  the  zero  of  the  verniers  coincide 
with  360 °,  180°,  etc.,  or  zero  of  the  divided  circle,  every  time 
any  angle  has  to  be  measured  in  traverse  or  circuitous  survey- 
ing, thus  reducing  the  time  and  labor  at  least  to  one-half  of 
that  required  by  the  use  of  other  classes  of  surveying-instru- 
ments, and,  at  the  same  time,  securing  greater  accuracy  and 
certainty  in  the  final  results. 

The  modus  operandi  is  simply  to  set  the  instrument  over  a 
station,  properly  level  it,  and  direct  the  lower  telescope  upon 
the  back-station,  and  the  upper  telescope  upon  the  fore-station, 
neglecting  the  vernier  readings  during  the  operation ;  then  a 
single  reading  determines  the  amount  of  the  observed  angle 
between  the  optical  axes  of  the  two  telescopes,  which  is  also 
that  between  the  two  stations.  If  the  observer  has  not  sufficient 
confidence  in  his  manipulation,  or  suspects  that  some  slight 
displacement  of  the  instrument  or  slipping  of  the  screws  has 
occurred  during  the  interval  of  the  observation,  he  may  decide 
the  question  instantaneously  by  applying  the  eye  to  each  tele- 
scope in  quick  succession,  when,  if  no  error  has  been  intro- 
duced, the  vertical  hairs  of  each  telescope  will  continue  to  strike 
through  each  station-mark.  If,  on  the  contrary,  any  slipping 
of  the  parts  of  the  instrument  has  resulted,  it  is  instantly  cor- 
rected by  applying  the  eye  first  to  the  lower  telescope,  bisecting 
with  the  body  tangent-screw,  and  then  to  the  upper  one,  per- 
forming the  same  operation  with  the  upper  tangent-screw.  Or, 
if  the  error  was  only  due  to  an  imperfect  observation  made 
with  the  upper  telescope,  the  last  operation  will  suffice  for  the 
correction.  However,  with  proper  care,  no  such  vitiating  error 
should  occur. 

It  is  apparent  that  with  the  use  of  a  theodolite  having  only  one 
telescope,  no  such  instantaneous  check-proof  can  be  obtained  at 
each  station,  at  least  without  reversing  the  telescope  from  the 
fore-  to  the  back-station,  or  vice  versa,  and  then  examining  the 
vernier-zero  in  order  to  determine  if  it  coincides  with  the  zero 
of  the  divided  circle  as  at  first  fixed.  Each  of  the  known 
modes  of  measuring  horizontal  angles  in  traverse  or  circuitous 
surveying  requires  two  separate  readings  before  an  angle  can 
be  determined.  This  would  be  the  case  when  the  vernier-zero 


102         THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

is  made  to  coincide  with  360°  at  only  the  first  angle,  and  when 
at  each  succeeding  station  each  preceding  angle  or  fore-reading 
is  made  to  become  the  back-reading  alternately.  For  the  engi- 
neer is  never  certain  that  some  slight  displacement  has  not 
occurred  during  the  transit  from  one  station  to  another,  due  to 
jarring  or  the  slipping  of  screws,  verniers  and  divided  circle, 
contraction  or  expansion  of  parts ;  or  it  may  be  that  the  opera- 
tor has  unconsciously  touched  the  tangent-screw  of  the  vernier 
and  divided  circle,  etc.,  rendering  a  constant  examination  of 
the  vernier-readings  an  absolute  necessity  for  both  back-  and 
fore-readings,  comparing  them  with  the  book-entries,  all  of 
which  means  a  waste  of  time  and  extra  mental  and  manual 
labor.  To  insure  absolute  freedom  from  error,  when  the  ver- 
nier-zero is  employed  for  all  the  back-observations,  it  is  neces- 
sary to  observe  the  supplementary  angle,  or,  at  least,  repeat  the 
angle,  either  of  which  would  involve  four  separate  operations 
and  readings. 

On  the  contrary,  even  when  the  supplementary  angle  is 
taken  by  the  theodolite  under  consideration,  Fig.  75,  only  two 
separate  readings  are  required.  For  example,  suppose  that  the 
angle  is  178°  35'  15",  and  the  supplementary  equals  181°  24' 
45",  then  178°  35'  15"  +  181°  24'  45"  =  360°,  as  it  ought 
to  be,  if  the  instrument  is  in  perfect  adjustment  and  the  manipu- 
lation is  correct.  Any  difference  from  an  entire  circle  would 
show  the  amount  of  error — plus  or  minus.  A  small .  amount 
of  error,  amounting  to  from  15"  to  20",  will  sometimes  exist, 
when  instruments  are  inferior,  and  is  difficult  to  eliminate. 
It  will,  therefore,  be  manifest  that  the  lower  telescope  is  capable 
of  rendering  incalculable  service. 

This  instrument  may  also  be  made  to  take  the  place  of  a 
transit-theodolite  for  a  variety  of  operations,  especially  in  pro- 
ducing transit  lines.  For  example,  when  it  is  necessary  to  pro- 
duce any  given  line — a  frequent  operation  in  a  certain  class  of 
surveys — it  is  done  by  first  placing  the  telescopes  to  look  in 
opposite  directions,  making  the  zeros  of  the*  three  verniers  of 
the  horizontal  circle  coincide  nicely.  The  lower  telescope  is 
then  directed  to  the  back-station ;  and  the  optical  axis  or  ver- 
tical wire  in  the  upper  telescope  points  out  the  direction  of  the 
transit  line.  The  verniers  being  double,  there  are  nine  distinct 
readings  by  which  to  effect  the  coincidence  before  producing  the 


THE    EVOLUTION   OF    MINE-SURVEYING   INSTRUMENTS.          103 

line ;  and  as  the  verniers  read  to  fifteen  seconds,  the  probable 
error,  plus  or  minus,  would  be  ^-  —  1.66  seconds.  It  is  doubtful 
whether  a  line  could  be  prolonged  by  a  transit-theodolite 
within  this  limit  of  error. 

"Where  townships  or  extensive  areas  of  land  are  required  to 
be  set  out  in  blocks,  this  instrument  would  prove  invaluable, 
for  the  reason  that  the  two  telescopes  may  be  set  at  right- 
angles  at  the  commencement  of  a  day's  work,  and  the  corre- 
sponding work  set  out  with  the  greatest  facility  and  accuracy. 
It  may,  however,  be  convenient  to  examine  the  vernier-readings 
as  the  work  proceeds. 

In  the  wide  arms  carrying  the  reading-microscopes,  and  just 
behind  each  of  them,  a  hole  is  drilled,  and  on  the  top  of  each 
hole  a  reflecting  prism  is  screwed,  having  a  horizontal  motion, 
so  that  each  of  them  may  be  turned  until  a  ray  of  light  is 
caught  and  reflected  upon  the  verniers,  which  are  thus  effectu- 
ally illuminated,  so  that  it  is  not  necessary  to  bring  the  light 
of  a  candle  or  lamp  inconveniently  near  the  head  when  the 
angles  are  read. 

When  the  instrument  is  used  on  the  surface,  the  long  or 
trough  magnetic  compass  is  slipped  into  a  corresponding  groove 
to  receive  it  under  the  horizontal  divided  circle,  or  on  the  top 
of  the  upper  telescope. 

By  preference,  a  triangular  leveling-  and  centering-frame  of 
light  weight,  with  three  leveling-screws,  is  attached  to  the 
theodolite,  Fig.  75.  The  conical  heads  of  these  screws  are 
locked  by  a  slipping  plate  into  a  similar  triangular  frame, 
which  is  screwed  to  the  top  of  the  tripod-stand.  This  leveling- 
frame  carries  two  other  thin  movable  plates,  and  vertical  pins 
working  in  elongated  slot-holes,  and  a  circular  clamping-ring. 
By  means  of  this  beautiful  apparatus,  invented  by  Troughton 
<fe  Simms,  the  instrument  has  a  free  motion  in  all  directions, 
carrying  the  plumb-line  and  bob  with  it,  and  can  thus  be  easily 
and  accurately  centered  over  a  fine  mark  made  in  the  station. 

Another  theodolite  of  this  class  is  now  in  course  of  con- 
struction by  Troughton  &  Simms,  and  more  closely  corre- 
sponds to  this  description  than  the  one  represented  by  Fig.  75, 
which  was  hastily  constructed  to  be  exhibited  at  the  Chicago 
Exhibition.  It  will  have  every  modern  improvement  that  the 
application  of  mathematical  principles,  mechanical  art,  and 


104         THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

good  workmanship  can  command,  or  exact  surveying  require. 
All  the  parts,  except  the  bearings,  axis  and  screws,  etc.,  are 
made  of  composite  aluminum  metal;  consequently,  weight 
should  not  now  be  considered  an  objection  to  the  general  use 
of  the  theodolite  for  mine-surveying.  Unfortunately,  however, 
this  kind  of  opposition  to  necessary  progress  will  still  continue 
in  various  quarters.  It  would  be  a  false  affectation  of  modesty 
not  to  note  that  American  and  other  authorities  have  decided 
that  this  type  of  instrument  is  the  best  English  theodolite  yet 
introduced  for  general  underground  and  surface-surveying. 

On  page  28  of  Mr.  Scott's  paper  reference  is  made  to  another 
quite  distinct  class  of  mine-surveying  instruments,  i.e.,  the  type 
known  as  theodolites  with  eccentric  telescopes  working  round 
the  circumference  of  the  divided  circle,  instead  of  over  its 
center.  The  French  appreciated  this  plan,  and  it  also  prevails 
in  Germany  to  a  considerable  extent.  The  great  objection  to 
French  instruments  of  this  class  is  the  dead  counterpoise- 
weights  that  they  are  obliged  to  apply  at  one  side  of  the  instru- 
ment, in  order  to  balance  the  telescope,  vertical  circle  and 
level  placed  on  the  opposite  side.  Combes  introduced  a  similar 
and  more  portable  instrument  of  this  type  for  mine-surveying 
in  1836.  Mr.  Scott  has  represented  it  in  Fig.  23  of  his  paper, 
as  also  the  double  target  for  sighting;  but  it  is  the  opinion  of 
the  writer  that  this  instrument  was  not  much  favored  out  of 
France.  Casella  also  introduced  in  1869,  for  the  use  of  trav- 
elers, a  very  small  instrument  of  this  kind,  superior  in  some 
respects,  but  inferior  in  others,  to  that  of  Combes.  It  is  well 
balanced,  but,  in  order  to  effect  this,  he  has  mounted  a  hori- 
zontal axis  over  and  across  the  diameter  of  the  magnetic  com- 
pass, with  a  level  on  the  top  of  the  axis  and  at  right-angles  to 
it.  This  axis  carries  a  telescope  on  one  side  and  a  vertical 
circle  on  the  other.  The  obstruction  due  to  the  horizontal  axis 
and  level  renders  the  instrument  of  no  value  as  far  as  the 
magnetic  compass  is  concerned. 

The  type  represented  by  Fig.  76  in  elevation  and  Fig.  77  in 
plan,  and  denominated  angleometer,  is  of  the  same  class  as  that 
of  Combes  and  Casella,  but  superior  in  construction  to  either. 
It  was  designed  by  the  writer  some  years  prior  to  1870,  and 
consists  of  a  divided  horizontal  circle,  vernier-circle  and  double 
vertical  axis,  mounted  upon  a  four-screw  leveling-base,  as  is 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


105 


common  in  theodolites.    The  horizontal  axis  carries  a  telescope 
at  one  side  of  the  horizontal  vernier-circle,  and  a  vertical  circle 

FIG.  re. 


HosKOLD's  ANGLEOMETER. 

with  sensitive  level,  attached  to  the  verniers  at  the  opposite  side. 
The  horizontal  axis  is  mounted  on  very  low  bearings,  a  little 
higher  than  the  diameter  of  the  axis,  and  screwed  to  the  upper 


106         THE    EVOLUTION   OF    MINE-SURVEYING    INSTRUMENTS. 


side  of  the  vernier-circle.  The  magnetic  compass  is  placed 
over  the  horizontal  axis,  and  almost  in  contact  with  it ;  the 
outer  ring  or  circular  portion  of  the  compass-box  is  continued 


FIG.  77. 


HosKOLD'S  ANGLEOMETER. 

down  to  meet  in  contact  with  the  vernier-circle  or  plate,  so  that 
the  axis  and  its  bearings  are  hidden  from  view.  The  magnetic 
needle  carries  a  very  light  and  delicate  circle,  as  in  a  prismatic 
compass,  with  vernier-readings;  but  verniers  reading  to  20 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


107 


seconds  are  preferable  to  the  circle.  The  particular  construc- 
tion of  this  instrument  insures  a  perfect  balance  of  the  parts, 
and  leaves  the  face  of  the  magnetic  compass  free  for  fine  mag- 
netic observations.  This  instrument  is  the  most  useful  of  its 


FIG.  78. 


SURVEYING  COMPASS. 


type,  especially  in  low  and  confined  roads  in  mines,  as  also  for 
connecting  the  first  line  in  an  underground  survey  to  the  sur- 
face by  direct  telescopic  sight  down  a  shaft.  It  is  also  well 
adapted  for  the  observation  of  stars  near  the  zenith  for  lati- 


108         THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

tude-  and  time-determinations.  It  was  a  patented  instrument, 
and  received  the  highest  award  in  the  Scientific  Instrument 
Section  of  the  London  Exhibition  in  1872. 

A  very  plain  and  useful  magnetic  compass,  Fig.  78,  was  also 
exhibited  at  the  same  time.  It  is  similar  in  construction  to 
the  angleometer,  without  the  theodolite  divided  circle.  The  hor- 
izontal axis  works  through  the  bottom  of  the  compass-box,  car- 
rying plain  sights  and  a  sensitive  spirit-level  on  one  side  and  a 
semicircle  with  verniers  and  clamp  tangent-screws  on  the  other. 
The  ordinary  levels  are  placed  in  the  compass-box.  The  in- 
strument was  afterwards  altered  by  adding  a  level  to  the  ver- 
nier-arm of  the  semicircle,  and  mounting  it  with  three  leveling- 
screws  in  the  same  manner  as  a  theodolite. 

The  great  objection  urged  against  the  use  of  the  eccentric 
theodolite  type  is  the  error  occasioned  in  the  angles  when  a 
telescope  works  round  the  limb  of  a  divided  circle  instead  of 
from  its  center.  Combes  avoided  this  error  by  the  use  of  his 
double  target.  The  writer  used  for  surface-work  station-poles 
with  double  points,  one  of  which  marked  the  station-point 
while  the  other  was  sighted  to.  For  underground  work,  a 
specially  constructed  lamp  and  apparatus  was  employed  for 
sighting-purposes,  the  lamp  being  removed  as  far  from  the 
station-point  as  the  distance  from  the  center  of  the  theodolite 
to  that  of  the  optical  axis  of  the  telescope.  When  the  angle- 
ometer was  used  in  connection  with  this  contrivance,  good 
results  were  obtained. 

However,  all  such  contrivances  may  be  avoided  by  observing 
the  horizontal  angles  between  the  stations  in  the  same  manner 
as  when  an  ordinary  theodolite  is  employed,  with  the  telescope 
over  the  center,  and  by  using  a  circular  protractor,  constructed 
with  a  radial  bar  carrying  another  bar  at  right  angles,  mounted 
with  folding  arms  and  pricker-points  to  move  round  the  circum- 
ference of  the  circle,  the  distance  from  the  center  to  a  line  pass- 
ing through  the  pricker-points  being  equal,  on  the  scale  of  the 
plotting,  to  that  from  the  center  of  the  angleometer  to  the 
optical  axis  of  the  telescope. 

It  would  occupy  too  much  space  to  attempt  to  describe  the 
construction  and  merits  or  demerits  of  all  the  forms  of  instru- 
ments which  have  been  proposed  to  be  employed  in  mine- 
surveying  from  time  to  time,  because  they  are  as  various  as  the 


THE    EVOLUTION     OF    MINE-SURVEYING   INSTRUMENTS.          109 

capricious  and  impracticable  ideas  of  those  who  attempted  to 
introduce  them.  Of  the  instruments  represented  by  Mr.  Scott's 
paper,  pp.  35  to  61,  Figs.  45  and  55  appear  to  the  writer  to  be 
the  least  cumbrous  and  most  useful.  At  the  same  time  we 
must  agree  that  Figs.  56  and  57  possess  the  merit  of  substan- 
tial construction,  and  doubtless  will  supersede  many  of  those 
previously  in  use  in  North  America.  The  form  exhibited  in 
Fig.  57  appears  to  be  preferable,  for  the  reason  that  the  writer 
has  been  unable  to  satisfy  himself  that  the  second  telescope 
attached  to  Fig.  56  is  absolutely  free  from  lateral  vibration. 
This,  however,  is  a  point  which  Mr.  Scott  may  be  able  to  clear 
up.  One  of  the  principal  features  in  most  North  American 
surveying-instruments  is  the  addition  of  a  second  or  auxiliary 
telescope  in  one  form  or  another,  intended  for  the  purpose 
of  making  a  connection  of  underground  workings,  one  with 
another,  by  sighting  down  steep  inclines  to  the  perpendicular, 
and  also  with  the  surface  by  sighting  down  a  shaft;  but  some 
of  the  modes  of  attachment  of  the  auxiliary  telescope  are  ex- 
ceedingly unsightly,  cumbrously  heavy,  and  are  also  uncertain 
in  action. 

So  far  as  the  writer  knows,  the  first  recorded  attempt,  in 
England,  to  perform  the  very  important  operation  of  producing 
a  surface-line  in  any  given  direction  underground  by  sighting 
down  a  shaft  is  to  be  found  in  a  book  by  C.  Bourns,  now  very 
scarce.*  It  was  performed  when  the  Box  Tunnel  was  con- 
structed by  the  Great  Western  Railway  Company,  England. 
Bourns  says : 

"  The  shafts  were  so  deep  (some  of  them  from  300  to  400  feet),  that  it  was 
found  the  plumb-lines  would  not  answer  the  purpose  on  account  of  oscillations 
caused  by  currents  of  air  or  otherwise  ;  the  following  method  was  therefore  re- 
sorted to,  viz.,  shafts  20  feet  in  diameter  were  sunk,  in  the  line  ;  the  center-line 
at  these  shafts  was  fixed  by  a  theodolite,  or  a  transit-instrument,  as  the  case  might 
be.  The  mode  of  accomplishing  this  will  be  understood  on  reference  to  the  figure 
[Fig.  79].  f  The  instrument  being  first  set  in  the  line,  on  the  surface,  at  A  or  B, 
and  a  point  fixed  in  the  bottom  of  the  tunnel  by  means  of  the  vertical  arc  ;  and 
then  another  point  found  in  a  similar  manner  from  the  other  side  ;  a  short 
length  of  line  was  thus  obtained,  which  was  carefully  produced  both  ways  to  meet 
other  portions  worked  from  the  adjacent  shafts.  These  points,  and  the  line 
through  them,  were  tested  at  every  length,  before  the  brick-work  was  put  in. 

*  The  Principles  and  Practice  of  Engineering  and  Other  Surveying,  C.  Bourns,  3d 
edition,  pp.  249,  250,  London,  1843. 
f  Copied  from  the  original. 


110         THE    EVOLUTION   OF    MINE-SURVEYING   INSTRUMENTS. 

When  a  shaft  is  so  deep  that  the  range  of  the  arc  of  a  theodolite  is  insuffi- 
cient to  enable  an  observer  to  see  to  the  bottom  of  a  tunnel,  a  transit-instrument 
must  be  made  use  of  instead." 

Such  is  the  description  given  by  Bourns  in  the  work  pre- 
viously referred  to.  It  is  highly  probable  that  the  transit-in- 
strument to  which  he  refers  was  similar  to,  or  at  least  some 
slight  modification  of,  Fig.  80,  which  is  copied  from  F.  "W. 
Sirnms's*  figure  of  an  instrument  made  by  Troughton. 

The  portable  meridian  transit  named  had  a  telescope  20 
inches  in  length,  with  a  diagonal  eye-piece  for  observation  in 

FIG.  79. 


\ 


DIAGRAM  ILLUSTRATING  BOURNS-S  METHOD. 

the  zenith  and  nadir.  The  circular  ring  base,  upon  which  the 
upper  parts  of  the  instrument  rested,  offered  great  facilities  for 
nadir-observations.  However,  considerable  time  was  expended 
in  bringing  the  optical  axis  of  the  telescope  to  the  vertical 
plane  of  the  line,  which  had  to  be  produced  down  a  shaft  into 
a  tunnel.  The  heavy  and  massive  base  now  attached  to  this 
class  of  instrument  renders  it  of  less  service  for  nadir-observa- 
tions than  the  old  pattern. 

Mr.  Beanlands,  however,  perfected  the  system  of  connecting 

*  A  treatise  on  the  Principal  Mathematical  Instruments  Employed  in  Surveying,  Level- 
ing and  Astronomy,  F.  W.  Sirnrns,  Ass't  at  the  R.  Observatory,  Greenwich,  p.  62, 
1836. 


THE   EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS.         Ill 


act  so. 


PORTABLE  TRANSIT  INSTRUMENT 

TROUGHTON 


surface-lines  with  underground  workings,  and  vice  versa,  and 
applied  it  to  mine-surveying  in  1856  with  great  success.* 

*  Trans.  North  of  England  Inst.  Mining  Engineers,  vol.  iv.,  pp.  267-273,  1856. 


112         THE    EVOLUTION   OF    MINE-SURVEYING   INSTRUMENTS. 

Many  years  since,  when  the  writer  occupied  himself  largely 
in  mine-surveying  with  various  kinds  of  instruments,  the  tele- 
scope of  his  angleometer  was  employed  to  fix  a  short  base-line 
in  shafts  not  more  than  10  feet  in  diameter.  The  two  points 
thus  set  out  were  used  to  drive  a  short  piece  of  tunnel  te  a 
point  where  the  longer  portion  of  the  tunnel  took  a  different 
direction.  The  third  point  or  station  at  the  bend  in  the  tunnel 
was  determined  by  stretching  a  fine  copper  wire  through  the 
two  points  previously  determined  at  the  bottom  of  the  shaft, 
and  from  this  third  station  the  principal  part  of  the  tunnel  was 
set  out,  the  direction  of  which  depended  upon  a  long  survey 
made  at  different  levels.  One  of  the  tunnels  referred  to  was 
over  300  yards  in  length,  and  when  the  workings  met  from  the 
two  sides  no  appreciable  difference  could  be  detected  in  the 
axial  direction  or  in  the  levels.  When  a  survey  is  conducted 
with  the  necessary  instruments  and  amount  of  care,  and  the 
system  of  co-ordinate  calculation  and  plotting  is  adopted,  and 
the  base  of  the  survey  is  no  longer  than  that  indicated,  the 
same  amount  of  precision  should  result,  though  the  tunnel 
were  ten  times  as  long. 

Similar  operations,  on  a  larger  scale,  were  carried  out  in 
driving  a  railway-tunnel,  three  miles  in  length  and  from  oppo- 
site points,  under  the  river  Severn,  in  England.  "When  the 
meeting-points  were  gained,  the  axial  line  of  the  tunnel  was 
perfect.  In  this  case  a  powerful  transit-instrument  similar  to 
Fig.  80  was  employed  to  fix  the  two  points  of  the  base-line 
transferred  from  the  surface  to  the  bottom  of  the  shafts. 

Various  other  cases  might  be  cited  to  prove  the  efficiency  of 
this  plan  of  making  connections,  which,  thanks  to  Bourns  and 
Beanlands,  will  never  be  superseded  by  any  other  method. 
The  only  difficulty  is  to  procure  a  sufficiently  portable  instru- 
ment capable  of  performing  this  operation,  as  well  as  all  others 
which  may  be  required  in  general  surveying. 

The  old  cradle-type  of  theodolite,  Fig.  17  in  Mr.  Scott's  paper, 
has  a  very  substantial  construction,  and,  as  now  made,  is  capable 
of  performing  excellent  results,  and  possesses  the  advantage  of 
resisting  a  good  deal  of  rough  work  before  becoming  impaired. 
If  an  extra  pair  of  Y's,  longer  than  those  at  present  employed, 
were  made  to  attach  and  detach  at  pleasure,  the  telescope 
could  be  thrown  forward  sufficiently  to  enable  an  observer  to 


THE    EVOLUTION   OF    MINE-SURVEYING   INSTRUMENTS.          113 

sight  down  a  shaft.  When  a  young  man,  the  writer  did  excel- 
lent work  with  this  class  of  instrument,  which  was  then  thought 
to  be  a  grand  acquisition.  For  general  underground  work  a 
5-in.  magnetic  compass  was  specially  made  to  attach  and  de- 
tach, by  means  of  screws,  at  the  top  of  the  telescope  of  this 
type  of  theodolite ;  and  by  this  mode  many  curious  and  erratic 
differences  were  discovered  in  the  direction  of  the  lines  as 
determined  by  the  theodolite-limb  and  the  magnetic  needle. 
The  magnetic  needle  was  read  by  means  of  a  strong  micro- 
scope, all  objects  of  iron  or  steel  being  removed  to  a  distance 
during  the  time  occupied  in  the  magnetic  observations. 

The  difficulty  experienced  by  Mr.  Scott  and  others  in  read- 
ing theodolites  more  finely  divided  than  to  single  minutes  is 
principally  due  to  the  result  of  the  divisions  being  placed  on 
the  flat  or  horizontal  upper  face  of  the  circle  instead  of  upon 
a  conical  or  beveled-edge  form,  as  is  generally  adopted  in  Eng- 
land, where  the  divisions  upon  flat  circles  have  been  aban- 
doned for  many  years  past. 

The  writer  does  not  agree  with  Mr.  Scott  in  the  opinion 
that  "  the  novice  is  generally  too  much  inclined  to  high  tele- 
scopic power  and  fine  graduations,  with  the  idea  that  greater 
accuracy  can  thus  be  attained,"  etc.  It  is  evident  that  if  Mr. 
Scott  could  be  certain  of  reading  the  observed  angle  in  all  cases 
to  a  minute  of  arc  precisely,  and  could  be  positive  that  nothing 
remained  which  could  be  determined  by  a  more  finely-divided 
vernier,  then  his  assertion  might  hold  good,  and  could  be 
boldly  urged ;  but  considering  that  frequently  it  is  difficult  to 
determine  with  absolute  precision  which  of  any  three  minute- 
divisions,  close  to  one  another,  is  the  one  most  nearly  in  coin- 
cidence with  a  division  upon  the  divided  circle,  it  is  manifest 
that,  in  the  majority  of  cases,  there  must  exist  a  small  angular 
quantity  which  a  vernier  divided  to  read  to  a  single  minute  ot 
arc  will  not  indicate,  and  which  must  remain  undetermined. 
This  small  angular  quantity  will  fall  between  one  and  fifty-nine 
seconds  in  the  minute-division  preceding  or  succeeding  to  that 
supposed  to  coincide  with  a  division  on  the  divided  circle. 
This  error  or  discrepancy  in  one  course  of  a  traverse  survey 
swings  the  whole  subsequent  portion  of  the  survey  round  by 
an  equal  angular  amount;  and  consequently  results  in  a  more 
prominent  error  in  long  surveys  than  in  short  ones. 


114         THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

To  illustrate  this  principle :  Supposing  that  the  observed 
angle  is  164°  31'  0",  and  the  supplementary  angle  195°  28' 
0",  then  164°  31'  +  195°  28'  equals  359°  59'  0",  or  one 
minute  in  defect ;  but  this  difference  of  one  minute  would  not 
have  been  known  without  taking  the  supplementary  angle.  On 
the  contrary,  employing  a  20-second  vernier,  we  find  the  first 
angle  to  be  164°  31'  40",  and  the  supplementary  angle,  195° 
28'  0";  and  164°  31'  40"  +  195°  28'  =  359°  59'  40",  which 
is  only  20  seconds  from  the  truth,  showing  clearly  that  this 
class  of  vernier-theodolite  is  at  least  twice  as  accurate  as  that 
with  a  minute-vernier.  Naturally  a  15-second  vernier  would 
give  closer  results.  For  example,  let  the  first  angle  observed 
be  164°  31r  40",  and  the  supplementary  angle  to  be  195°  28' 
15",  then  164°  31'  40"  +  195°  25'  15"  =  359°  59'  55",  or 
only  5  seconds  from  forming  an  entire  circle.  The  use  of  a 
minute-vernier  could  not  give  such  a  close  approximation  to 
the  truth.  We  find  that  in  all  high-class  surveying  the  most 
accurately  divided  instruments,  with  fine  readings  and  corre- 
sponding optical  power,  are  adopted.  We  cannot  afford  to 
become  inattentive  to  well-established  principles  and  practice, 
nor  can  it  be  permitted  to  descend  in  the  scale  of  progression 
and  agree  that  a  five-  or  ten-minute  vernier  is  as  good  as  one 
divided  to  single  minutes ;  for  in  that  case  we  should  go  on 
degenerating  until  we  accepted  Bibero's  division  to  a  single 
degree,  or  Digges's  to  a  two-degree  division. 

It  is  true,  there  is  a  medium  course,  and  an  instrument 
adapted  to  one  class  of  work  may  not  be  the  best  for  a  different 
class  of  work.  It  is  necessary,  therefore,  to  determine  the 
fineness  of  the  divisions  of  a  theodolite-circle  and  vernier  ac- 
cording to  the  nature  of  the  work  and  the  degree  of  accuracy 
sought  to  be  attained.  An  error  of  one  minute  would  be 
serious  on  very  long  lines,  if  any  important  work  depended 
upon  the  survey,  such,  for  example,  as  a  long  tunnel  driven 
from  opposite  ends,  or  the  fixing  of  boundary-lines  at  a  remote 
point  between  two  or  more  rich  mines ;  especially  if  the  region 
to  be  surveyed  were  not  an  open  one,  free  from  such  obstacles 
as  would  prevent  checking  by  trigonometrical  observations. 
During  more  than  half  a  century  of  experience  with  various 
kinds  of  instruments,  the  writer  has  never  experienced  incon- 
venience in  reading  theodolites  of  4  in.  in  diameter,  divided  to 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS.         115 

• 

read  to  20  seconds  of  arc,  and  to-day  he  finds  no  difficulty  in 
reading  a  5-second  vernier  attached  to  a  transit-theodolite  of  8 
in.  diameter,  which  he  sometimes  employs  for  simple  trigono- 
metrical and  astronomical  observations.  However,  a  good  deal 
depends  upon  habit.  The  best-sized  theodolite  for  general 
underground  and  surface  work  is  from  5J  to  6  in.  in  diameter, 
reading  to  either  15  or  20  seconds,  and  this  gives  ample  space 
between  the  divisions  for  facile  reading  with  strong  micro- 
scopes. Such  surveying-instruments  are  now  preferred  in 
nearly  all  parts  of  the  world.  To  avoid  scratching,  as  far  as  is 
possible,  the  best  metal  to  divide  upon  is  platinum,  and  with 
gold  verniers  a  more  facile  means  of  reading  is  afforded. 

Mr.  Scott  passes  lightly  over  the  sub-tense  system  of  deter- 
mining distances,  probably  for  the  reason  that  his  single-minute 
theodolite  would  not  command  the  process.  Nevertheless,  in 
the  opinion  of  the  writer,  as  previously  observed,  this  is  a  most 
accurate  and  facile  system,  as  has  been  proved  on  the  great 
Indian  surveys.  The  writer  has  pointed  out  what  kind  of 
apparatus  is  required  in  connection  with  a  theodolite  for  per- 
forming it.  The  micrometer-microscope  attached  to  the  eye- 
piece of  the  theodolite  of  the  writer,  now  in  construction  and 
similar  to  Fig.  75,  is  all  that  is  necessary.  Such  a  simple 
auxiliary  may  be  applied  to  any  theodolite,  and  may  be  con- 
structed to  measure  to  one  second  of  arc  or  less. 

If  it  is  required  to  measure,  by  the  instrument  shown  in  Fig. 
75,  an  angle  smaller  than  15  seconds,  the  micrometer  attached 
to  the  eye-end  of  the  telescope  is  employed  in  the  following 
manner :  Suppose  that  the  vertical  hair  intersects  a  station- 
mark,  and  the  reading  is  believed  to  vary,  plus  or  minus,  from 
exactly  15,  30  or  45  seconds.  The  vernier-circle  is  turned 
backwards  until  the  verniers  mark  the  nearest  of  these  num- 
bers. The  vertical  hair  should  then  appear  out  of  contact  with 
the  station-mark ;  and  the  small  distance  from  the  permanent 
vertical  hair  in  the  telescope  to  the  station-mark  is  measured 
with  the  micrometer.  Let  this  measure  be  11.6  seconds,  and 
the  previously  measured  angle  174°  10'  30",  then  the  entire 
angle  would  be  174°  10'  41". 6.  For  instruments  of  small 
size  this  is  a  more  convenient  plan  than  that  of  attaching  long 
and  powerful  micrometrical  microscopes  to  read  the  horizontal 
circle  instead  of  verniers ;  because  such  an  arrangement  renders 

9 


116         THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

• 

the  instrument  more  costly,  cumbrous,  bulky,  and  liable  to  get 
out  of  order. 

The  following  is  an  example  of  the  Tanner  mode  of  deter- 
mining distances : 

Measured  angle,  3°  KK  31".  4  ;  sub-tense  base,  30  meters. 

Then  log.  of  the  base  of  30  meters,        ....       1.4771213 
And  log.  co-secant  ot  3°  10' 31  ".4,          ....     11.2565632 

Log.  of  the  distance  required, 2.7336845 

Distance  required,        u      •„>>.!'.     .£;!  ;v/^       .         .541.60725 

The  average  of  several  measurements  of  the  angle  should  be 
employed.  When  the  distant  point  is  in  an  elevated  place,  the 
length  of  the  line  to  be  determined  would  be  that  of  the  hy- 
pothenuse  of  a  vertical  right-angled  triangle,  and  should  be  re- 
duced to  the  horizontal  by  the  ordinary  rule. 

Cook  &  Sons,  of  York,  introduced  some  years  since  a  new 
model  of  surveying-instrument  of  the  transit-type,  the  standards 
or  Y's  of  which,  and  the  vernier  circle,  are  cast  in  a  single 
piece,  insuring  great  stability  and  freedom  from  vibration. 
The  lower  circle  has  a  square  outer  edge,  similar  to  a  thin 
cylinder,  and  the  divisions  are  marked  upon  the  upper  portion 
of  the  square  edge,  so  that  the  vernier,  being  also  square-edged, 
fits  so  nicely  that  the  division  line  between  vernier  and  cir- 
cle is  almost  imperceptible.  The  vertical  circle  is  divided  in  a 
similar  form.  The  divisions  are  read  either  by  direct  sight 
through  horizontal  microscopes  or  by  perpendicular  sight 
through  prismatic  microscopes.  The  instrument  of  this  class, 
formerly  used  by  the  writer,  had  very  low  Y's,  without  transit- 
movement,  and  was  found  to  be  a  very  efficient  instrument. 

The  writer  cannot  agree  with  Mr.  Scott's  opinion  upon  Ever- 
est's theodolite,  which  is  a  very  elegant,  useful  and  light  instru- 
ment. "No  one  knew  better  than  Everest  what  was  required 
for  filling-in  surveys  in  a  hot  climate  like  that  of  India.  The 
instrument  is  constructed  to-day  with  divisions  upon  a  beveled- 
edge  circle,  and  has  other  improvements ;  and  when  the  coun- 
try to  be  surveyed  is  not  very  mountainous,  as  in  England  and 
in  a  large  part  of  the  Argentine  Republic  and  other  surround- 
ing republics,  this  instrument  is,  and  could  be  further,  used 
with  great  advantage,  especially  when  the  lines  are  long  and 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS.          117 

the  engineer  becomes  fatigued  from  excessive  heat  in  passing 
from  station  to  station.  Under  such  circumstances,  any  one 
would  endeavor  to  avoid  the  extra  weight  unavoidable  in  heavy 
transit-theodolites.  However,  circumstances  must  decide  what 
instrument  is  best  adapted  to  a  certain  place  and  class  of  work. 

As  all  practical  engineers  know,  all  underground  surveys 
should,  if  possible,  be  conducted  in  a  circuitous  traverse  form, 
always  seeking  to  finish  at  the  point  of  commencement ;  the 
corrections  of  all  the  angles  may  then  be  determined  before 
leaving  the  mine,  or  at  least  before  plotting  the  work.  The 
sum  of  the  internal  angles,  treated  by  the  well-known  rule, 
will  exhibit  any  error  which  may  exist,  plus  or  minus.  If  none 
such  can  be  found,  and  the  plotting  will  not  agree,  then  the 
error  must  be  sought  for  in  the  measure  of  the  lines  and  not  in 
the  angles.  Long  before  1863,  the  writer  advocated  that  the 
first  underground  line — continued — should  be  made  a  com- 
mon base  to  which  all  the  underground  and  surface-surveys 
should  be  referred;  that  is  to  say,  this  line  should  be  laid 
down  as  a  common  meridian  prolonged  throughout  the  plan, 
from  which  line  all  the  angles  observed  underground  and  on 
the  surface  should  be  plotted.  In  that  year  he  published  this 
system,  demonstrating  its  great  utility  and  superiority,  and 
showing  that  no  accumulation  of  error  could  exist,  as  is  too 
frequently  the  case  when  the  co-ordinate  system  of  plotting  is 
not  adopted.  This  plan  only  requires  that  all  the  observed 
horizontal  angles  should  be  reduced  in  such  a  manner  that 
they  are  in  a  proper  condition  to  be  set  off  or  plotted  from  this 
first  line,  assumed  as  a  common  meridian  for  the  whole.  More- 
over, as  this  is  the  line  which  should  be  produced  upon  the 
surface  by  the  process  already  noted,  it  is  the  fittest  to  be 
selected  for  this  object.  However,  with  proper  care  the  same 
reduced  horizontal  angles  referred  to  may  be  plotted  from  this 
base-line  by  a  single  setting  of  a  circular  protractor  and  similar 
good  results  obtained.  All  that  is  required,  in  addition,  is  a 
long  and  accurately-made  metal  parallel  ruler  of  sufficient 
weight  to  run  parallel  upon  a  board  20  feet  long,  without  devi- 
ation, to  transport  the  angles  to  the  plotting-points  or  artificial 
stations  on  the  paper. 

A  protractor  similar  to  Fig.  81,  which  was  constructed  for  the 
writer  many  years  since  by  Messrs.  Troughton  &  Simms,  is  well 


118         THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

adapted  for  this  class  of  work.  It  is  10  inches  in  diameter, 
divided  upon  a  silver  beveled  edge,  and  reads  by  two  verniers 
to  ten  seconds.  The  folding  arms  are  mounted  at  each  end  by 
.a  screw  carrying  fine  pencil-points  for  marking  off  angles,  in- 
stead of  using  steel  points.  The  readings  of  the  circle  are 
aided  by  two  strong  microscopes,  revolving  in  arms  round  the 
circle.  When  the  protractor  is  fixed,  it  is  kept  in  position  by 
very  fine  needle-points  screwed  into  the  sides  of  the  instrument 
and  taking  hold  of  the  paper ;  or  two  weights  may  be  applied. 
The  beveled  edge  of  the  circle  offers  greater  facility  in  read- 
ing than  when  the  divisions  are  placed  upon  a  horizontal  or  flat 
surface.  There  is  also  cast  at  one  side  of  the  circle  a  bracketed 
projecting  piece  of  brass  with  a  beveled  edge  forming  a  line  a 
little  longer  than  the  diameter  of  the  circle,  and  set  parallel  to 

Fie.  81. 


HOSKOLD-S    CIRCULAR  PROTRACTOR. 

a  line  passing  through  the  360°  and  180°  divisions.  This  use- 
ful appendage  enables  the  draughtsman  to  slide  the  instrument 
along  a  steel  straight-edge,  previously  placed  against  the  meri- 
dian line,  with  the  view  of  plotting  some  of  the  angles  from  more 
than  one  position  or  station,  when  they  are  very  numerous,  and 
the  pencil-dots  representing  them  come  too  close  together. 
The  instrument  has  a  clamp  and  tangent-screws,  with  a  spring 
attached. 

If  either  of  the  modes  of  working  indicated  in  the  foregoing 
remarks  were  always  employed,  using  the  theodolite  to  observe 
the  angles,  independent  of  magnetic  bearings,  no  need  could 
exist  for  the  true  or  magnetic  meridian ;  but  as  some  people 
will  always  have  a  fancy  for  the  use  of  the  magnetic  compass, 
its  corresponding  meridian,  as  also  the  true  meridian,  may  be 


THE    EVOLUTION   OF    MINE-SURVEYING   INSTRUMENTS.          119 


FIG.  82. 


determined  and  laid  down  upon  mining  plans,  at  least  as  an 
ornament,  and  to  satisfy  curiosity  or  other  exigencies. 

The  writer  desires  that  this  contribution  shall  be  taken  as  an 
independent  paper  upon  mine-surveying  and  instruments,  as 
well  as  representing  his  part  of  the  discussion  of  Mr.  Scott's 
paper,  which,  in  his  opinion,  is  a  very  creditable,  useful  and 
important  production. 

MR.  SCOTT  :  I  think  that  I  shall  voice  the  sentiments  of  the 
Institute  at  large  when  I  take  this  occasion  to  thank  Gen.  Hos- 
kold  for  his  very  elaborate  and 
scholarly  contribution  to  the 
topic  I  was  trying  to  cover  in  a 
few  pages.  His  description  of 
the  old  manner  of  conducting 
underground  surveys  by  the 
graphic  method  of  snapping 
chalk-lines  on  the  top  of  a  3- 
legged  stool  is  very  interesting. 
No  doubt  this  was  the  practice, 
as  he  explains,  before  Hough  ton 
wrote  his  fifty-nine  articles  on 
the  "  Laws  and  Customs  of  the 
Wapentake  Lead-Mines ;"  but  is 
it  not  more  reasonable  to  sup- 
pose that  it  found  its  rise  in  the 
systems  of  plane-table  surveying 
that  were  in  vogue  nearly  a 
hundred  years  before  ? 

I  am  of  the  firm  belief  that  the  science  of  mine-surveying  in 
all  its  forms,  as  well  as  all  the  instruments  devised  to  facilitate 
the  art,  were  in  nearly  every  case  derived  from  some  method 
previously  pursued  in  field,  geodetic  or  astronomical  surveying. 
Thus,  as  he  has  recorded  here,  the  astrolabes  exhibited  by  the 
British  Museum  date  back  to  the  llth  century;  while  the  oldest 
instrument  of  this  class  that  I  know  of  as  being  employed  in 
mine-surveying  is  one  described  by  Yoigtel  in  the  first  edition 
of  his  work  (1686)  as  something  new — of  such  recent  manu- 
facture, in  fact,  that  he  was  unable  to  include  it  in  its  proper 
place  in  the  14th  chapter  of  the  work,  which  treats  of  the  use 


Voigtel's  Mining  Astrolabe. 


120         THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

of  two  or  more  Scheiben  in  conducting  surveys  in  iron-mines. 
Voigtel  says  : 

"It  is  a  newly-invented  instrument,  by  use  of  which  the  operations  in  iron- 
mines  are  conducted  still  more  accurately  than  by  any  of  the  methods  previously 
described.  It  is  divided  into  360  degrees.  Through  its  center  is  a  hollow  tube, 
as  high  as  the  diameter  of  the  plate,  extending,  one-half  above  and  one-half 
below,  at  right-angles  to  the  plate,  tapering  somewhat  toward  its  extremities. 
Through  the  tube  two  waxed  threads  are  drawn  and  tied  at  the  ends,  one  set 
extending  forward,  the  other  backward ;  and  into  these  loops  the  measuring- 
cord  or  chain  is  hooked  when  at  work.  About  the  tube  revolves  an  index-arm, 
extending  somewhat  beyond  the  plate,  so  that  when  the  cords  are  pulled  taut  in 
operation,  it  can  reach  them,  and  the  horizontal  angle  can  be  read  as  indicated, 
even  if  the  courses  are  elevated  or  depressed  as  much  as  45°.  Then  there  is  a 
base  with  a  wooden  screw,  so  that  the  instrument  can  be  set  up  on  any  timber- 
ing in  which  an  auger  has  previously  bored  a  hole.  The  base  has  a  movable 
ball-and-socket  joint  with  four  screws  (as  shown  in  Fig.  83),  so  that  the  instru- 
ment can  be  properly  secured  for  horizontality  by  means  of  a  bubble-tube — too 
well  known  to  require  special  illustration  or  description." 

Mr.  Hoskold's  verifying  or  lower  telescope,  set  so  as  to  be 
always  coincident  with  the  zero  of  the  vernier,  is  apparently  a 
very  ingenious  contrivance,  and  of  great  convenience  in  taking 
back-sights ;  but  why  does  he  not  adopt  Mr.  Wagoner's  cyclo- 
tomic  circles  with  it,  so  that  the  azimuth  axis  (which  must  now 
of  necessity  be  inverted  between  the  standards)  may  be  dis- 
pensed with,  thereby  making  his  theodolite  a  transit  instru- 
ment ?  While  the  matter  is  now  before  us  I  would  advance 
the  proposition  that  this  cyclotomic  principle  is  the  only  correct 
one  yet  devised  for  nadir-instruments  in  which  the  vernier-cir- 
cles are  to  be  preserved ;  for  the  perforation  in  the  simple  ver- 
tical axis  may  be  large  enough  for  all  practical  purposes  with- 
out perceptibly  increasing  the  size  of  the  base.  The  A.  Lietz 
Co.,  422  Sacramento  Street,  San  Francisco,  Cal.,  will  be  glad 
to  furnish  full  information  concerning  the  means  whereby  a 
repetition-theodolite  may  be  constructed  upon  a  single  axis  of 
revolution. 

I  cannot  permit  myself  to  enter  into  a  prolonged  discussion 
upon  the  relative  merits  for  mining  work  of  minute-graduations 
as  compared  with  those  of  finer  divisions.  On  this  point  nearly 
every  engineer  has  an  individual  opinion  very  difficult  to  influ- 
ence one  way  or  the  other.  The  reason  I  advocate  minute- 
graduations  is  because  the  possible  error  of  the  angular  meas- 
urements is  substantially  as  small  as  that  of  the  linear  ones. 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS.          121 

A  100-foot  steel  tape  divided  into  lOths  and  lOOths  of  a  foot 
is,  I  believe,  most  generally  used  by  American  engineers  for 
the  measurement  of  underground  courses.  In  a  5-inch  circle, 
graduated  to.  read  minutes,  the  maximum  error  will  probably 
not  exceed  30  sec.,  whose  corresponding  lineal  error  in  an 
average  course  of  from  50  to  100  feet  can  scarcely  be  detected 
on  a  tape  of  the  above  description.  Many  American  engineers 
have  been,  and,  I  believe,  are  still  using  a  chain  underground;* 
but  there  is  no  sense  in  too  highly  refining  the  instrument 
while  the  means  of  measurement  are  in  so  many  cases  quite 
rude. 

It  seems  strange  that  Mr.  Hoskold  should  declare  himself 
favorably  inclined  toward  Figs.  45  and  55,  and  object  to  my 
interchangeable  auxiliary,  when  placed  on  top  of  the  main 
telescope  under  conditions  almost  identical  with  the  others 
mentioned.  There  is  no  form  of  detachable  top-telescope  con- 
ceivable to  me  in  which  the  possibilities  of  lateral  vibration  are 
so  completely  removed.  The  vertical  pillar,  to  which  the  aux- 
iliary is  firmly  screwed  and  clamped,  is  cast  in  one  piece  with 
the  telescope-hub,  just  as  are  the  horizontal  axes,  and  there  is 
no  more  possibility  of  vibration  in  one  than  in  the  other.  Figs. 
45  and  55  are,  as  I  have  said,  in  my  opinion,  excellent  types; 
but  neither,  I  believe,  is  so  simple  in  construction,  nor  can 
either  be  used  at  the  side  if  occasion  should  require  it.  There 
is  no  room,  certainly,  for  a  distinction  between  Figs.  56  and 
57;  for  they  are  the  same  instrument,  and  the  construction  and 
method  of  application,  as  well  as  the  means  of  adjustment,  are 
precisely  similar. 

As  to  Everest's  theodolite,  all  I  have  said  about  it  is  on  p.  697 
of  my  paper,  and  amounts  to  nothing  more  than  a  simple  state- 
ment that  the  instrument  "  practically  became  obsolete  twenty 
years  ago."  Beyond  what  this  statement  might  be  deemed  to 
imply,  I  expressed  no  "  opinion  "  whatever. 

JAS.  B.  CoopERf  (communication  to  the  author) :  If  Mr. 
Hoskold  is  correct  in  saying  that  the  first  instruments  used  for 
surveying  consisted  of  two  movable  cross-bars  of  wood  or 


*  Report  on  Mining  Methods,  etc.,  in  the  Anthracite  Coal-Fields,  H.  M.  Chance, 
Harrisburg,  Pa.,  1883,  p.  371. 

t  Supt,  Calumet  and  Hecla  Smelting- Works,  South  Lake  Linden,  Mich. 


122         THE    EVOLUTION   OF    MINE-SURVEYING   INSTRUMENTS. 

metal,  fixed  to  the  top  of  a  rod,  then  we  have  here  in  Fig.  83 
a  survival  of  the  most  ancient  method  ever  used. 

All  the  figures  given  in  this  cut  (though  rearranged  to  suit 
the  present  need)  are  taken  from  Tab.  XI.  of  the  Mathema- 
tischer  Atlas  by  Tobias  Mayer,  Philomath,  Augsburg,  1744. 
The  lower  figure  represents  the  cross-staff  as  described  by  him. 
It  consisted  of  two  plain  brass  rules  pivoted  upon  each  other 

FIG.  83. 


Astrolabium  and  Cross-Staff  from  Mayer's  Math.  Atlas,  1744. 

near  one  end,  as  shown,  and  provided  with  simple  sights  at 
each  extremity.  From  the  center,  N",  were  marked  off  very 
accurately  the  points  M  and  L,  so  that  they  should  be  equidis- 
tant from  the  center.  In  whatever  relative  position,  then,  the 
rules  might  be  placed,  "N  M  and  N"  L  would  always  be  equal 
and  mark  the  sides  of  an  isosceles  triangle  whose  base,  L  M, 
would  naturally  vary  in  proportion  to  the  size  of  the  angle 
measured  through  the  sights.  "When  the  sights  had  been  fixed 
very  carefully  on  their  respective  objects,  a  pair  of  compasses 
was  employed  to  measure  the  distance  L  M,  which  was  at  once 


THE    EVOLUTION   OF    MINE-SURVEYING   INSTRUMENTS.          123 

determined  in  terms  corresponding  to  the  other  sides  upon  the 
scale  I K,  after  which  the  angle  M  N  L  was  calculated. 

This  instrument  was  mounted  upon  the  tripod  shown,  the 
construction  of  which,  as  Mayer  says,  is  too  well  known  to  de- 
mand special  description. 

This  tripod  was  likewise  used  with  the  Astrolabium,  which  he 
also  introduces,  and  was  so  constructed  that  the  spindle  at  the 
head  could  be  tipped  to  a  horizontal  position  for  the  measure- 
ment of  vertical  angles.  He  says  : 

' '  For  the  measurement  of  angles  in  the  field  and  for  the  laying  out  of  the  same 
we  use  the  astrolabium.  It  is  usually  made  of  brass,  though  sometimes  also  of 
wood,  and  has  a  diameter  of  from  8  to  1 2  inches,  divided  into  360  deg. ,  and  by 
use  of  the  diagonal  scale,  G,  to  10  or  even  5  min.  of  arc.  At  each  quadrant  are 
placed  the  diopters  A,  B,  C,  and  D,  and  from  the  center  revolves  the  rule  E  F, 
at  the  ends  of  which  are  also  placed  two  diopters  somewhat  higher  than  the 
others.  The  observations  are  read  to  10  minutes  of  arc,  with  the  20°  diagonal 
scale  ;  by  which  it  will  appear  that  the  line  G  H,  for  instance,  marks  the  angular 
value  of  22°  20V 

This  is  a  method  of  reading  angles  not  mentioned  by  Mr. 
Scott ;  but  I  am  undecided  as  to  whether  it  has  an  individuality 
all  its  own,  or  is  only  a  modification  of  the  nonius  he  has  de- 
scribed on  pp.  59,  60.* 

i 
W.  S.  HUNGERFORD,  Jersey  City,  K.  J.  (communication  to 

the  Secretary) :  In  connection  with  the  very  able  and  complete 
paper  of  Mr.  Scott  on  "  The  Evolution  of  Mine-Surveying  In- 
struments," a  short  description  of  the  instruments  and  method 
employed  by  the  writer,  some  fifteen  years  ago,  at  the  iron- 
mines  of  Low  Moor,  Ya.,  of  which  he  was  superintendent,  may 
be  of  interest. 

In  the  mines  referred  to  there  were  several  main  track-levels 
approximately  parallel  and  about  100  feet  apart  vertically,  and 
at  varying  horizontal  distances,  according  to  the  dip  of  the 
vein,  which  was  from  50°  to  75°.  Between  these  levels  there 

*  SECRETARY'S  NOTE. — The  diagonal  scale  (or  method  of  transversals,  as  it  is 
sometimes  called),  is  said  by  Thos.  Digges  (Alee  seu  Scalce  Mathematics,  Capitulum 
Nonum,  Londini,  1573),  to  have  been  invented  by  Richard  Chanzler,  an  English 
artist  famous  for  his  skill  in  the  construction  of  mathematical  instruments,  and 
to  have  been  long  well  known  in  England.  See  Robert  Grant's  History  of  Physical 
Astronomy,  London,  1852,  p.  442.  For  these  facts  I  am  indebted  to  Mr.  B.  S.  Ly- 
man,  of  Philadelphia,  Pa.— R.  W.  R. 


124         THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

were  frequent  upraises,  and  these  again  connected  by  frequent 
levels  and  workings  of  great  irregularity  and  often  difficult  of 
access,  but  all  of  which  it  was  desirable  to  keep  promptly  sur- 
veyed and  plotted.  The  entrances  of  the  main  track-levels 
were  either  on  the  open  side-hill  or  connected  by  a  vertical 
hoisting-shaft.  The  main  levels  were  all  connected  carefully 
with  a  transit-and-level  survey  with  frequent  permanent  marks ; 
these  levels,  ending  at  the  hoisting-shaft,  being  oriented  by 
means  of  two  plumb-wires,  as  described  in  Borchers's  Mark- 
scheidekunst,  p.  143.  The  accuracy  of  this  orienting  was  tested 
upon  the  opening  of  the  first  upraise  to  the  next  higher  level 
and  found,  in  a  traverse  of  about  a  mile,  to  close  within"  4 
inches.  The  transit  surveys  were  carefully  calculated  by  lati- 
tudes and  departures,  referred  to  an  astronomically  determined 
meridian,  and  plotted  in  three  projections. 

The  transit  used  was  an  11-cm.  instrument  made  by  Aug. 
Lingke,  of  Freiberg,  Germany,  in  1877.  The  horizontal  circle 
was  graduated  from  0°  to  360°  and  read  by  two  verniers  to 
single  minutes,  as  was  also  the  vertical  circle.  A  fixed  reading- 
glass  and  a  reflector  were  used  for  each  vernier.  With  prop- 
erly adjusted  reflectors  there  should  be  no  difficulty  in  getting 
the  light  on  the  verniers  without  burning  the  face.  The  ver- 
nier-readings could  easily  be  estimated  to  30  seconds,  and  by 
repeating  the  angles  and  taking  the  mean  readings  an  accuracy 
of  15  seconds  was  attainable.  By  using  rather  high  standards 
an  angle  of  depression  of  52°  was  secured;  but  beyond  this  no 
provision  was  made  for  observing  very  steep  angles.  The 
transit  had  no  magnetic  needle,  and  the  telescope  was  invert- 
ing. The  writer  would  add  his  endorsement  to  all  that  Mr. 
Scott  has  said  in  favor  of  this  form  of  telescope.  The  usual 
objection  that  the  inverting  of  the  object  is  likely  to  cause  con- 
fusion is,  in  the  experience  of  the  writer,  entirely  unfounded. 

The  intermediate  upraises,  levels  and  workings  were  sur- 
veyed by  means  of  the  cord,  steel  tape,  hanging-compass  and 
clinometer,  of  course  using  every  available  opportunity  to 
check  the  work  by  connecting  to  the  more  accurately  deter- 
mined points  of  the  transit-survey.  The  inclined  distances 
were  reduced  to  the  horizontal  and  vertical  by  means  of  the 
trigonometer  and  the  hanging-compass.  The  compass  was 
designed  to  stride  the  transit  at  pleasure,  as  also  to  be  used 


THE    EVOLUTION   OF    MINE-SURVEYING   INSTRUMENTS.          125 

interchangeably  in  a  brass  protractor-plate  for  plotting,  care 
being  taken  that  the  drawing-table,  stands,  etc.,  contained  no 
iron  nails,  screws  or  bolts.  There  was  no  local  magnetic 
attraction  in  the  mines ;  but  in  a  few  instances,  where  rails  or 
other  iron  material  influenced  the  needle,  perfectly  satisfactory 
results  could  be  obtained  by  a  slight  variation  of  the  method 
and  by  taking  the  magnetic  bearing  at  each  end  of  the  cord. 
This  method  was  found  abundantly  accurate  for  filling  in 
between  the  transit-surveys ;  it  was  expeditious  and  entirely 
mechanical,  and  could  be  used  in  places  where  a  transit  could 
hardly  be  taken.  In  fact  the  assistant,  a  bright  young  man 
taken  from  the  mining  force,  was  soon  able  to  make  and  plot 
these  compass-surveys,  and  give  the  necessary  directions  for 
upraises,  etc.,  without  any  aid  from  the  writer.  If  it  was  de- 
sired to  connect  a  point  in  one  level  with  a  point  in  another 
level  by  an  upraise,  the  magnetic  bearing  between  the  two 
points  could  be  taken  directly  from  the  horizontal  projection, 
and  from  the  known  horizontal  and  vertical  distances  the 
angle  of  inclination  of  the  upraise  could  be  drawn  on  paper, 
and  a  triangular  piece  of  board  could  be  cut  to  correspond  and 
given  to  the  mine-foreman,  who  had  only  to  keep  one  side 
level,  and  the  other  on  a  straight  edge,  to  get  the  required  in- 
clination. 

In  this  connection  a  simple  device  of  the  writer  for  control- 
ling the  grade  of  a  level  under  construction  may  be  worthy  of 
mention.  The  average  miner,  working  in  a  level,  has  very 
little  idea  of  grade,  except  as  he  sees  the  water  run ;  and 
although  the  average  grade  may  be  very  accurately  controlled 
by  the  chain  and  leveling-instrument,  there  may  occur  very 
annoying  variations  between  the  visits  of  the  engineer,  par- 
ticularly if  the  work  is  rapid.  One  must  change  these  at  much 
expense,  or  leave  a  permanent  defect  in  a  track  over  which 
many  thousand  tons  of  material  may  have  to  be  moved.  The 
grade  of  the  level  having  been  determined  upon,  a  wedge- 
shaped  straight-edge  is  prepared  of  convenient  length,  say  12 
feet,  wider  at  one  end  than  the  other  by  the  amount  of  the 
grade  in  its  length.  Thus,  if  the  grade  is  1  in  400,  and  the 
straight-edge  12  feet  long  and  6  inches  wide  at  one  end,  it 
would  be  6.36  inches  wide  at  the  other  end.  The  miner  has 
simply  to  drive  wooden  leveling-pegs  about  12  feet  apart,  level- 


126         THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

ing  the  top  of  the  straight-edge  with  a  spirit-level,  with  which 
he  is  provided,  and  driving  the  front  peg  down  or  cutting  it 
off  at  the  proper  height.  The  miner  has  no  linear  measure- 
ments to  take,  as  the  exact  distance  apart  of  the  leveling-pegs 
has  no  influence  upon  the  grade.  It  was  surprising  to  find 
how  uniform  a  grade  was  thus  obtained,  and  how  slight  a  cor- 
rection was  required  by  the  later  instrumental  surveys. 

MR.  SCOTT  :  Mr.  Hungerford  admits  that  the  greatest  angle 
of  depression  possible  with  his  instrument  was  52°.  By  force 
of  circumstances,  then,  he  was  required  to  employ  the  Gradbogen 
in  connection  with  it,  to  determine  dips  as  great  as  75° — as  an 
expedient,  I  should  say,  rather  than  a  convenience. 

I  am  convinced  that  in. the  use  of  fixed  reading-glasses  there 
is  no  danger  of  losing  them ;  that  they  are  always  in  focus, 
that  one  hand,  which  would  otherwise  be  engaged,  is  left  free, 
and  that  a  considerably  higher  power  is  possible,  while  the 
field  still  remains  flat  though  somewhat  diminished  in  size. 
Strictly  speaking,  fixed  reading-glasses  with  a  properly  adjusted 
reflector,  mounted  behind  them  upon  the  radial  arm  of  the 
socket,  are  a  European  innovation ;  and  while  my  previous  re- 
marks were  based  upon  an  unsuccessful  experience,  it  may  be 
that  with  the  great  majority  of  American  engineers  I  shall 
some  day  learn  to  adopt  them.  If  Americans  were  generally 
more  eager  to  adopt  some  of  the  more  cumbersome  and  tedious 
of  the  German  appliances  and  methods  there  would  be  no  occa- 
sion for  a  diversity  of  opinion  as  to  the  correct  method  of 
illuminating  and  reading  the  verniers. 

Herr  Max  Harrwitz  has  sent  me  from  Berlin  a  description 
of  Jahr's  theodolite,*  in  which  we  have  an  instance  of  the  ex- 
tremes that  are  resorted  to  by  the  profound  and  ingenious  Ger- 
mans to  effect  a  desired  end.  Suspended  to  the  Stengelhaken 
(a,  Fig.  84)  is  a  small  wooden  box  in  which  the  electric  current 
is  produced  in  two  J-ampere  accumulators  that  are  set  into 
hard-rubber  cells.  From  this  source  two  leading  wires  (Z/), 
positive  and  negative,  are  led  each  to  one  of  two  metal  rings  (d 
and  e)  that  are  separated  by  a  little  strap  and  countersunk  into 
a  hard-rubber  plate  (c).  The  connections  of  the  leading  wires 

*  Given  in  JDer  Mechaniker,  vol.  vi.,  No.  18.  Sept.,  1898  (from  Zeitschr.  fur 
Vermessungswesen ) . 


THE    EVOLUTION. OF    MINE-SURVEYING   INSTRUMENTS. 


127 


with  the  accumulator  poles  are  made  through  casings  at  st.  The 
hard-rubber  plate  is  attached  by  three  screws  (n)  to  the  base  of 
the  theodolite,  and  is  perfectly  concentric  with  the  axis  of  the 
instrument.  Upon  the  metal  rings  revolve,  as  desired,  two 
contact  springs  (/)  which  are  rigidly  attached  to  the  upper  part 
of  the  theodolite,  and  by  means  of  wires  are  connected  with  the 

FIG.  84. 


Illuminating  Apparatus  of  Mine-Surveyor-General  Jahr,  of  Breslau,  Germany. 

switch  (g)  and  the  lamps  (h  and  i).  By  the  switch  either  of  the 
lamps  can  be  turned  on  as  required.  The  portable  box  (6),  in- 
cluding accumulators  and  fixtures,  weighs  about  2.75  kg.,  or  a 
little  over  6  pounds.  On  the  upper  side  of  the  box  is  a  rheostat 
to  regulate  the  current.  Both  incandescent  lamps  may  be  fed 
from  8  to  10  hours  continuously,  so  that  if  one  required  two 


128         THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

minutes  to  read  both  verniers,  one  charging  of  the  accumu- 
lators would  be  sufficient  for  from  240  to  300  readings. 

Of  late  several  American  engineers  have  been  using  small 
portable  electric  lamps,  of  the  dry  storage-battery  type,  with 
great  advantage  and  convenience.  The  one  used  with  much 
satisfaction  by  the  writer  is  made  by  the  American  Endoscopic 
Co.,  of  Providence,  B.  I.  It  weighs  only  0.6  kg.,  and  has  a 
small,  8-candle  power  incandescent  bulb  with  silvered  parabolic 
reflector,  that  will  burn  continuously  for  8  hours.  The  lamp 
has  two  batteries,  one  of  which  may  be  in  use  while  the  other 
is  getting  charged.  A  small  switch  at  the  side  of  the  box 
turns  the  light  on  or  off  as  desired,  the  current  being  con- 
tinuous and  the  illumination  brilliant.  The  entire  length  of 
the  box  is  6  inches,  and,  having  a  cross-section  of  only  1J  by  3 
inches,  it  can  be  very  conveniently  carried  in  the  pocket.  There 
is  a  detachable  bulb  at  the  end  of  a  flexible  cord,  which  may  be 
arranged  so  as  to  leave  both  hands  entirely  free. 

The  chief  merit  of  this  lamp  consists  in  the  great  conveni- 
ence of  its  small  size  compared  with  its  efficiency. 

Another  portable  electric  lamp  is  made  by  Elmer  E.  Mc- 
Intyre,  of  Pittsburgh,  Pa.,  and  has  a  small  bulb  and  white 
enameled  reflector  mounted  on  a  stick-pin,  so  that  it  may  be 
attached  to  the  hat  or  any  part  of  the  clothing.  The  battery- 
case  is  strapped  around  the  waist,  and  weighs  1.4  kg.  It  is  of 
4  c.  p.,  and  is  designed  to  burn  10  hours,  though  in  reality  it 
falls  decidedly  short  of  that.  To  recharge  the  battery,  it  is 
removed  from  the  case  and  the  positive  and  negative  poles  are 
connected,  by  means  of  a  specially  provided  intermediate 
socket,  to  an  incandescent  lamp  on  any  110-volt  direct-current 
circuit.  The  amount  of  voltage  and  amperage  that  the  larger 
lamps  consume  afterwards  passes  into,  or  through,  the  coils  of 
the  battery. 

By  the  use  of  such  portable  electric  lamps,  the  dimness  of 
flickering  candle-lights,  the  dripping  of  grease  and  the  crude 
features  of  all  other  methods  of  illumination  are  forever  done 
away  with,  except  for  those  who  will  persist  in  magnetic  sur- 
veys and  the  necessary  bulky  copper  oil-lamps.  But  in  these 
cases  may  we  not  say,  in  general,  that  the  method  of  illumina- 
tion is  in  consistent  keeping  with  this  awkward  system  of 
surveying  ? 


THE    EVOLUTION   OF    MINE-SURVEYING   INSTRUMENTS.          129 

J.  E.  JOHNSON,  Longdale,  Ya.  (communication  to  the  Secre- 
tary) :  The  paper  of  Mr.  Scott  has  evidently  been  prepared 
with  much  care,  and  displays  such  a  comprehensive  knowledge 
of  the  subject  that  one  has  a  feeling  of  trepidation  at  criticising 
any  part  of  it.  Nevertheless,  I  am  compelled  to  take  issue 
with  one  paragraph,  namely,  the  second  on  page  25,  which  is 
as  follows : 

"In  recent  years  the  hanging-compass  has  been  redesigned  by  Queen  &  Co.,  of 
Philadelphia,  and  is  said  to  be  still  indispensable  to  certain  surveyors  in  Virginia 
and  Pennsylvania.  The  excuse  for  employing  the  hanging-compass  in  cramped 
and  tortuous  channels  to-day,  however,  seems  absurd  ;  for  the  transit  can  be  made 
to  do  the  most  reliable  work,  even  when  removed  from  the  tripod,  anywhere  that 
a  man  can  take  it." 

This  paragraph  indicates  a  misconception  as  to  what  is  pos- 
sible and  what  is  commercially  practicable;  in  other  words, 
what  pays.  It  also  seems  to  indicate  that  the  words  "  cramped 
and  tortuous  "  might  have  decidedly  different  meanings  in  dif- 
ferent mining  regions. 

There  is  no  doubt  that,  given  unlimited  time  and  unlimited 
expenditure  for  general  and  local  appliances  and  support,  a 
transit-survey  can  be  made  of  any  hole  that  a  man  can  crawl 
through ;  but  there  is  also  no  doubt  that,  with  a  hanging-com- 
pass outfit,  when  running  on  short  lines  between  definitely- 
located  points,  work  which  is  substantially  accurate  and  en- 
tirely within  the  needs  of  ordinary  commercial  engineering 
can,  in  many  cases,  be  done  in  as  many  minutes  as  the  tran- 
sit-survey would  require  hours.  To  explain  the  circumstances 
under  which  this  is  true  within  the  writer's  own  knowledge,  it 
will  be  necessary  to  give  a  brief  resume  of  the  paper  to  which 
Mr.  Scott  alludes,  in  a  footnote,  as  having  been  published  in 
The- Engineering  and  Mining  Journal,  August  1, 1891,  taken  from 
Transactions  of  the  American  Institute  of  Mining  Engineers*  The 
paper  was  written  by  Mr.  Guy  R.  Johnson,  then  engineer  for 
the  Longdale  Iron  Company,  of  this  place,  now  General  Man- 
ager of  the  Embreville  Iron  Company,  of  Tennessee,  and  the 
mines  described  by  him  were  those  of  the  former  company. 

The  mines,  like  others  in  the  Oriskany  or  brown  ore-deposits 
in  this  State,  have  for  their  objective  a  stratum,  rather  than  a 

*  Trans.,  xx.,  96. 


130         THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

vein,  of  ore  taking  the  place  of  the  Oriskany  sandstone,  and 
lying  immediately  under  the  black  slate  [Rogers'  !N"o.  Yin.] . 
The  exact  nature  of  the  stratum  as  to  thickness,  dip,  conti- 
nuity, etc.,  varies  in  each  case  with  the  mountain  in  which  the 
particular  mine  is  located.  Locally,  the  ore-stratum  is  vertical 
or  even  dipping  toward  the  mountain  at  its  southwest  end,  and 
gradually  twists,  like  a  huge  "  warped  surface  "  or  a  helix  of 
very  high  pitch,  as  it  goes  northeast,  lying  at  an  average  incli- 
nation of  about  35°  at  its  extremity  in  that  direction.  The 
stratum  is  entered  at  intervals  of  120  feet  vertically  by  tunnels 
through  the  slate,  which  of  course  follow  the  ore  after  they 
reach  it,  generally  keeping  the  bottom  inner  corner  of  the  tun- 
nel just  along  the  foot-wall.  The  irregularities  in  places  are 
extreme,  the  tunnel  being  in  a  number  of  places  at  right-angles 
to  its  proper  general  direction,  and  in  a  few,  pointing  the  oppo- 
site way. 

The  main  tunnels  are  connected  at  intervals  of  approxi- 
mately 120  feet  horizontally  by  a  pair  of  upcasts — one  called, 
locally,  the  "  chute,"  the  other  the  "  man-way."  Along  with 
the  main  heading,  after  the  ore  is  reached,  is  driven  another 
about  20  feet  above  it,  called  the  "  air-way."  Subsequently 
other  levels  are  driven,  all  at  intervals  of  20  feet  vertically, 
making,  of  course,  five  between  each  pair  of  main  levels.  It 
is  impossible  to  describe  the  operation  properly  without  some 
reference  to  time  and  the  consecutive  order  of  the  operations, 
and  it  should  be  said  that  the  mine  is  worked  down  in  success- 
ive levels,  each  main  entry  being  driven  when  there  is  still 
several  years'  ore  in  sight  in  the  one  above.  The  main  entry 
and  air-way  are  carried  on  together,  as  stated,  and  as  fast  as 
they  reach  the  proper  points  for  the  upcasts,  these  are  started 
and  cut  through  to  the  main  entry  next  above  for  ventila- 
tion, etc.  The  levels  above  the  air-way  are  driven  approxi- 
mately in  the  order  of  their  heights  above  the  main  entry,  so 
that  it  may  be  a  year  or  two  after  the  main  entry  passes  a  given 
chute  before  the  "  100-foot  level "  reaches  it.  After  a  given 
section  has  been  developed  in  this  way  to  its  extremities,  the 
20-foot  pillars  are  "  split,"  and  then  "  robbed,"  beginning  at  the 
top,  of  course,  and  working  down. 

In  surveying  the  mine  a  transit-line  is  first  run  with  some 
care  in  the  main  entry,  putting  nails  in  the  ties,  instead  of  the 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS.          131 

collars  or  "  caps,"  as  the  ties  are  very  much  less  likely  to  move 
or  break ;  and  in  using  wire  nails  instead  of  tacks  it  is  remark- 
able how  seldom  points  are  lost,  even  after  the  lapse  of  many 
months,  or  even  two  or  three  years.  The  passing  of  all  chutes 
and  man-ways  is  noted  on  the  transit-survey. 

Starting  at  these  points,  a  string-survey  is  taken  through 
them,  taking  the  bearing,  inclination  and  length  on  the  string. 
The  passing  of  all  the  levels  is  carefully  noted,  and  the  distance 
of  the  string  above  the  bottom  of  the  level  at  the  point  taken 
as  the  intersection  is  noted  also.  Subsequently  the  compass  is 
removed  from  the  gimbals,  fitted  with  standard-sights,  and 
mounted  upon  a  small  tripod  with  a  ball-joint  connection. 
The  levels  above  the  main  entry  are  then  run  out,  sighting 
from  the  compass  forwards  and  backwards  at  lamps  held  in  the 
center  of  the  level,  thus  taking  both  a  "  back  sight "  and  a 
"  fore  sight,"  as  with  a  transit,  but  only  setting  up  at  alternate 
stations.  This  saves  one-half  of  the  number  of  "  set-ups," 
and  avoids  the  error  of  not  setting  the  compass  vertically  over 
the  point  last  sighted  at,  an  error  liable  to  occur  when  only 
taking  foresights.  The  points  noted  as  the  intersections  when 
making  the  string-survey  are  located  on  the  tripod-compass- 
survey  of  the  levels  by  eye,  and  notes  of  their  location  taken. 

This  will  doubtless  seem  to  many  mining  engineers  a  bar- 
barous method,  and  from  the  point  of  view  of  absolute  accu- 
racy undoubtedly  it  is,  as  compared  with  making  a  transit- 
survey  of  the  whole  mine — chutes,  secondary  levels  and  all; 
but  the  remarkable  thing  about  it  is  the  accuracy  which  may 
be  obtained  in  this  way.  It  should  be  noted  that  the  length 
of  each  individual  string-survey  is  only  from  120  to,  at  most, 
250  feet,  and  that  when  the  upcasts  are  cut  through  to  the 
main  entry  next  above,  the  upper  end  of  the  survey  can  be 
connected  with  a  known  point  on  the  transit-survey  of  that 
entry. 

By  the  aid  of  a  trigonometer,  or  mechanical  traverse-table, 
the  horizontal  and  vertical  lengths  of  the  inclined  sights  are 
obtained  and  plotted ;  first  as  a  "  plan,"  or  map,  reduced  to  a 
horizontal  plane,  and  from  this  and  the  vertical  components  of 
the  sights  an  elevation  is  constructed ;  also  cross-sections,  when 
necessary.  It  should  have  been  said  also  that  a  line  of  levels 
is  run  into  the  main  entries,  and  the  elevation  of  the  top  of  the 

10 


132         THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

rail  is  taken  at  all  chutes,  to  form  the  basis  for  the  elevations 
derived  from  the  respective  string-surveys. 

Moreover,  with  regard  to  the  barbarous  practice  of  locating 
the  intersections  of  the  upcasts  and  secondary  levels  at  the 
same  point  in  space  by  eye,  I  would  say  that  never  more  than 
a  thousand  feet  per  year  of  the  mine  are  opened  up  in  the  way 
described ;  that,  as  the  survey  is  brought  up  to  date  every  year, 
there  are  comparatively  few  new  upcasts  and  a  correspondingly 
small  number  of  intersections  to  carry  in  one's  head  during 
the  period  elapsing  between  making  the  string-survey  of  the 
upcasts  and  the  compass-survey  of  the  secondary  levels ;  and 
that,  owing  to  the  rapidity  with  which  the  work  can  be  done  in 
this  way,  this  period  is  very  short — not  over  a  few  days.  It  is 
needless  to  remark  that  one's  memory  would  not  be  equal  to 
the  task  for  the  period  required  if  a  transit  were  used. 

It  is  also  to  be  noted  that  the  iniquity  of  using  this  method 
is  largely  counterbalanced  by  the  fact  that  a  variation  of  a  few 
inches,  or  even  a  couple  of  feet,  with  the  compass  will  simply 
result  in  displacing  the  line  parallel  to  itself  by  that  amount ; 
whereas  with  a  transit,  on  lines  of  the  same  length,  averaging, 
perhaps,  20  feet,  the  same  error,  swinging  the  entire  remain- 
ing portion  of  the  line  through  a  corresponding  angle,  would 
make  the  results  so  obtained  worse  than  useless.  Again,  there 
is  a  fair  chance  with  the  compass  that  the  errors  will  balance 
one  another,  but  practically  none  with  the  transit. 

As  a  matter  of  actual  experience,  surveys  so  made  plot  on 
paper  with  a  degree  of  accuracy  that  is  almost  surprising,  the 
intersections,  as  noted  on  the  two  surveys  in  which  they  occur, 
coinciding  so  closely  as  frequently  to  be  almost  within  the 
errors  of  plotting.  For  the  purposes  for  which  the  survey  and 
map  are  designed — that  is,  to  show  the  progress  and  shape  of 
the  mine,  to  give  directions  for  cutting  new  passage-ways  of 
moderate  length  when  necessary,  and  .to  show  the  mine  as  it 
practically  is — this  system  of  surveying  is  as  useful  and  satis- 
factory as  it  would  undoubtedly  be  preposterous  if  applied  for 
the  location  of  points  to  hit  exactly  with  Vertical  bore-holes,  or 
for  similar  absolutely  accurate  work. 

It  would  undoubtedly  be  possible,  as  observed  in  the  begin- 
ning, to  carry  a  transit-survey  through  these  mines  or  any  others; 
but  the  difficulties  of  the  process  would  be  immense.  The 


THE    EVOLUTION   OF    MINE-SURVEYING   INSTRUMENTS.          133 

chutes  and  man-ways  are  "  cribbed  up,"  when  it  is  necessary  to 
timber  them,  3  J  feet  square  inside.  They  follow  the  flexures 
of  the  foot-wall  of  the  ore  in  one  direction,  and  sometimes, 
unfortunately,  the  equation  of  personal  error  of  the  miner  or 
foreman  in  the  other,  and  occasionally  even  both  at  once ;  so 
that  the  bends  are  sometimes  very  short,  especially  in  the  ver- 
tical plane.  Frequently,  of  course,  these  bends  occur  when 
the  chute  is  nearly  or  quite  vertical,  and  the  difficulties  of  get- 
ting satisfactory  readings  with  compass  and  clinometer  are  very 
great;  and  a  survey  of  accurately-fixed  points  with  a  mining- 
transit,  capable  of  use  throughout  the  entire  vertical  plane,  dis- 
mounted from  its  tripod  (the  only  way  it  could  be  taken  through 
or  set  up),  would  be  a  matter  of  an  indefinite  amount  of  prepa- 
ration for  each  sight,  and  unlimited  time  and  expense.  In  the 
matter  of  time,  it  is  necessary  to  note  that  the  chutes  are,  nor- 
mally, more  or  less  filled  with  ore,  and  must  be  specially  emptied, 
with  inconvenience  and  loss  of  time,  in  order  to  be  surveyed  at  all. 

Something  over  a  year  ago  it  became  desirable  to  connect 
two  main  entries  by  a  transit-line,  and  so  a  man-way  was  cut 
with  especial  care  to  keep  it  straight  and  have  the  inclination 
sufficiently  uniform  to  be  within  the  vertical  range  of  a  standard 
transit  (without  other  attachment  than  those  appertaining  to 
the  ordinary  horizontal  and  vertical  circles) ;  but  in  spite  of 
these  precautions,  and  the  simplicity  of  the  problem  pre- 
sented in  surveying  the  opening,  the  time  consumed  in  the 
operation  was  an  earnest  of  what  it  would  be  to  do  the  same 
thing  in  steeper  and  more  tortuous  places. 

In  view  of  these  facts,  I  must  beg  Mr.  Scott  to  believe  that 
there  is  a  field,  small  in  size  and  importance  as  compared  with 
the  Lake  Superior  region,  perhaps,  in  which  the  hanging-com- 
pass has  a  respectable,  if  not  exalted,  sphere  of  activity  and 
usefulness  still  left  to  it,  and  in  which,  for  the  purposes  of  what 
may  fairly  be  called  commercial  engineering,  it  is  far  better 
than  any  form  of  transit  ever  yet  designed  or  ever  likely  to  be. 

JULIUS  KELLERSCHON*  (communication  to  the  author) :  Be- 
ing assured,  by  the  contributions  from  Messrs.  Hungerford  and 
Johnson,  that  in  various  parts  of  America  the  old  German 
method  of  cord-surveying  is  still  used  to  apparent  advantage 
for  certain  kinds  of  work,  I  take  this  opportunity  to  submit 

*  Mining  Engineer,  Oliver  Mining  Company,  Irbnwood,  Mich. 


134         THE    EVOLUTION   OF   MINE-SURVEYING   INSTRUMENTS. 


what  I  believe  to  be  the  first  English  translation  of  the  text  in 
Prof,  von  Miller-Hauenfels's  work*  that  relates  to  the  rules  of 
which  Mr.  Scott  has  spoken  on  page  9. 

It  is  not  quite  just  to  ascribe  to  Prof.  Hauenfels  the  entire 
credit  Mr.  Scott  has  given  him ;  for  investigations  in  a  scientific 
and  systematic  manner  had  been  conducted  some  time  before 
the  beginning  of  this  century,  as  will  appear  below.  But  the 
Leoben  professor,  no  doubt,  was  the  first  to  get  complete  infor- 
mation on  the  subject  in  comprehensive  form  for  the  use  of  the 
student  and  practitioner.  He  closes  his  remarks,  however,  with 
an  observation  to  the  effect  that  the  varying  tension  on  the 
cord,  its  hygrometric  conditions,  etc.,  must  still  be  considered 
before  the  discussion  can  be  accepted  as  closed.  He  says : 

' '  The  experiments  executed  in  this  line  show  that  the  Gradbogen  suspended  in  the 
exact  center  of  the  cord  will  cause  the  vertical  component  to  be  too  small  and  the 
horizontal  too  large ;  but  the  corrections  which  practical  work  actually  requires  are 
considerably  greater  than  those  provided  for  in  the  theoretical  formulas  of  the  cate- 
nary curve.  The  reason  for  this  is  that  the  hook  at  the  higher  end  depresses  the 

cord  more  than  the  lower  one.  If,in  the  ac- 
companying diagram  (Fig.  85),  a  and  b  are 
the  points  from  which  the  Gradbogen  is 
suspended  ;  c,  the  point  from  which  the 
plummet  is  suspended  ;  d,  the  center  of 
gravity  of  the  Gradbogen;  Q,  the  weight 
of  it ;  q,  the  weight  of  the  plummet,  and/, 
h,  i  and  g  the  projections  of  the  points  a, 
c,  d  and  b  on  a  horizontal  line,  then  the 
weight  which  draws  vertically  at  the  point 

b  may  be  expressed  by  _ -  (fh  .  q  +/i  .  Q\ 

/9 
and  the  weight  which  draws  vertically  at 


FIG.  85. 


Diagram  of  Gradbogen. 


the  point  a  by  —  (kg 


q+ig.  Q).      The 


sum  of  these  two  expressions  would  be,  as  it  ought  to  be,  the  total  weight  of  Grad- 
bogen and  plummet.  As  fh  and  hg  do  not  differ  much  in  length,  and  the  weight 
q  is  inconsiderable  as  compared  with  Q,  it  is  mostly  the  leverage/^  and  eg  which 
decides  the  depression  caused  by  the  hooks  a  and  b.  Thus  the  higher  hook,  b, 
will  depress  the  cord  in  proportion  to  the  degree  of  the  inclined  angle.  In  a  very 
steep  angle  it  can  reach  a  condition  where  ig  will  be  negative  ;  that  is,  the  lower 
hook  will  have  a  tendency  to  rise  above  the  cord,  and  in  such  cases  it  must  be  fast- 
ened to  prevent  this. 

"The  first  experiments  along  this  line  were  made  several  decades  ago  by  the 
late  Mr.  Florian,  of  Bleiberg,  in  Carinthia.  He  made  known  to  several  of  his 
acquaintances  the  results  of  his  very  laborious  and  precise  experiments,  but  I  was 
unable,  in  spite  of  many  inquiries,  to  obtain  a  copy  of  his  original  manuscript. 


Hohere  Markscheidekunst,  Albert  von  Miller-Hauenfels,  Wien,  1868,  pp.  286- 


291. 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


135 


The  resulting  rule,  however,  was  communicated  to  me  by  the  kindness  of  Berg- 
hauptmann  E.  Hiibel,  of  Olmiitz,  who  found  it  in  the  memoirs  of  his  late  father- 
in-law,  Bergrichter  von  Hohenfels.  Florian's  rule  is  as  follows  : 

* ' '  To  find  the  true  vertical  angle  of  the  cord,  the  Gradbogen  should  be  suspended  ap- 
proximately one  decimal  inch  from  the  center  of  the  cord  toward  the  higher  end  of  it  for 
every  degree  of  inclination,  so  that,  at  45°,  it  will  be  suspended  50  decimal  inches  from 
the  center  of  the  cord. ' 

"The  weight  of  the  Gradbogen  is  in  this  case  taken  as  7  Loth.*  The  length  of 
the  cord  is  not  given  in  Florian's  calculations ;  but  it  seems  that  it  did  not  exceed 
8  Klafter  (fathoms) ;  for  there  is  a  remark  to  the  effect  that  this  length  should  not 
be  exceeded  in  determining  vertical  heights. 

"In  the  Berg-  und  Huttenm.  Zeitung,  No.  7,  1862,  Prof.  A.  Junge  published  ex- 
periments also  along  this  line.  He  measured  accurately  the  vertical  and  hori- 
zontal components  of  cords,  3  to  7  Freiberg  Lachterf  long,  subjected  to  a  tension 
of  20  kg.,  and  from  these  figures  calculated  the  true  length  of  the  cord,  as  well  as 
the  angle  of  inclination,  comparing  these  with  the  angles  as  actually  read.  We 
take  from  his  table  the  following  figures,  and  add  a  few  columns,  which  will  form 
the  basis  of  our  further  consideration  : 


8 

Inclined  Angle. 

a  . 

m 

•2 

o> 

. 

*§  § 

Q    "   • 

Q    '    • 

_! 

I 

i 
H 

o 
to 

igth  of  Cord 

ulated. 

is  Read  at 
r  of  Cord. 

EH   tifl 

"I 
$& 

| 

f 

asion  Point 
ed  by  Factoi 
each  Degree 

rage  Values 

tision  Point 
ed  by  Factoi 
each  Degree 

jrage  Values 

,8 

3 

1 

.2,1 

II 

5 

||«2 

£ 

|'P 

> 
<J 

§ 

^ 

J* 

co£ 

GO  <u 

1 

6.80 

1°41' 

1°39' 

0.552 

0.505 

0.507 

2 

6.81 

3°  22' 

3°  21' 

0.526 

0.510 

0.513 

3 

6.83 

5°  03' 

5°  03' 

0.500 

0.515 

0.520 

4 

6.85 

6°  43' 

6°  42' 

0.531 

0.520 

0.527 

5 

6.87 

8°  22' 

8°  21' 

0.539 

0.525 

0.533 

6 

6.90 

10°  00' 

10°  00' 

0.500 

0.525 

0.530 

0.518 

0.540 

0.523 

7 

6.94 

11°  38' 

11°  36' 

0.569 

0.535 

0.546 

8 

6.98 

13°  14' 

13°  12' 

0.564 

0.540 

0.553 

9 

7.03 

14°  50' 

14°  48' 

0.592 

0.544 

0.559 

10 

7.09 

16°  23' 

16°  21' 

0.581 

0.549 

0.565 

11 

7.15 

17°  56' 

17°  54' 

0.569 

0.554 

0.572 

12 

7.21 

19°  26' 

19°  24' 

0.558 

0.572 

0.558 

0.547 

0.578 

0.562 

13 

6.17 

24°  54' 

24°  51' 

0.600 

0.575 

0.593 

14 

6.99 

23°  38' 

23°  36' 

0.563 

0.571 

0.594 

15 

7.43 

23°  48' 

23°  45' 

0.586 

0.571 

0.595 

16 

7.15 

26°  34' 

26°  33' 

0.526 

0.580 

0.606 

17 

7.60 

26°  34' 

26°  30' 

0.616 

0.579 

0.606 

18 

6.72 

30°  23' 

30°  21' 

0.563 

0.576 

0.591 

0.578 

0.621 

0.603 

19 

6.38 

32°  12' 

32°  09' 

0.600 

0.596 

0.629 

20 

5.72 

36°  28' 

36°  24' 

0.653 

0.609 

0.646 

21 

5.56 

37°  42' 

37°  39' 

0  667 

0.613 

0.651 

22 

5.40 

38®  59' 

38°  57' 

0.587 

0.627 

0.617 

0.609 

0.656 

0.645 

23 

4.67 

46°  44' 

46°  42' 

0  598 

0  640 

0  687 

24 

4.53 

48°  35' 

48°  33' 

0  598 

0.646 

0.694 

25 

4.40 

50°  32' 

50°  30' 

0.598 

0.598 

0.651 

0.646 

0.702 

0.694 

26 

3.94 

59°  32' 

59°  30' 

0  667 

0  678 

0.738 

27 
28 

3.85 
3.77 

62°  06' 
64°  48' 

62°  03' 
64°  48' 

0.630 
0  500 

0.686 
0  694 

4 

0.748 
0.759 

29 

3.49 

76°  46' 

76°  45' 

0.729 

0.631 

0.730 

0.697 

0.807 

0.763 

*  One  German  pound  or  £  kg.  is  equal  to  16  Loth. 

i  One  Freiberg  Lachter  is  equal  to  two  metres,  or  6.56  feet. 


136         THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

"  The  first  four  columns  require  no  explanation.  The  fifth  shows  the  point  of 
the  cord,  expressed  in  decimal  parts  of  it,  at  which  the  Gradbogen  should  be  sus- 
pended in  order  to  obtain  a  true  reading,  as  shown  in  the  third  column. 

"The  values  in  the  fifth  column  have  been  computed  by  Prof.  Junge  from 
readings  made  at  the  center  and  both  ends  of  the  cord,  according  to  Lagrange's 
interpolation-formula.  We  agree  with  Prof.  Junge  that  the  point  for  the  sus- 
pension of  the  Gradbogen,  under  the  same  conditions,  should  be  removed  from  the 
center  upward,  in  proportion  to  the  length  of  the  cord,  which  theory  has  also 
been  verified  by  Borchers  (see  Berg-  u.  Hilttenm.  Zeit. ,  No.  25,  1863)  ;  and  it  is  to 
be  pronounced  an  omission  by  Florian  that  in  formulating  his  rule  he  took  no  ac- 
count of  this  important  fact.  On  the  other  hand,  we  take  issue  with  Prof.  Junge 
that  he  has  not  sufficiently  emphasized  the  effect  of  the  increasing  vertical  angle 
upon  the  correction  to  be  made,  to  which  Florian  has  attached  the  most  im- 
portance. In  a  word,  Florian  says  the  Gradbogen  should  be  suspended  one  deci- 
mal inch  from  the  center  for  every  degree  of  inclination  ;  while  Junge  summarizes 
his  experiments  with  the  assertion  that  it  should  be  suspended,  on  an  average,  0.58 
of  the  length  of  the  cord  from  the  lower  end. 

' '  To  combine  these,  we  must  consider  whether  the  absolute  values  given  by 
each  correspond.  For  the  angle  'of  45°  in  Florian's  rule,  with  the  correction  of 
50  decimal  inches,  the  values  given  by  each  are  respectively  as  accurate  as  could 
be  desired.  By  Junge' s  twenty -third  experiment,  in  which  the  angle  is  46°  42', 
the  distance  of  the  suspension-point  from  the  center  is  given  at  0.098  of  the  length 
of  the  cord  ;  that  is,  in  this  case,  4.67  X  .098  =  0.458  Freiberg  Lackter,  or  0.458  X 
1.024  =  0.47  Weimar  Klafter.  Now,  according  to  Florian,  the  suspension-point 
should  have  been  0.52  Weimar  Klafter  from  the  center  of  the  cord  ;  but  if  we 
consider  that  Florian  used  a  longer  cord,  as  well  as  that  the  average  values  in  the 
sixth  column,  twenty -third  experiment,  represent  one  of  those  cases  in  which  the 
point  of  suspension  has  been  given  by  Prof.  Junge,  no  doubt,  a  little  too  low,  we 
may  safely  say,  as  to  Florian's  correction-limit,  that  nothing  better  could  be 
desired. 

"Using  Florian's  rule,  we  find  that  by  it,  and  on  the  basis  of  Junge's  experi- 
ments, the  best  results  are  obtained  if  the  number  of  degrees  and  fractions 
thereof,  as  read  at  the  center  of  the  cord,  are  multiplied  by  the  factors  0.003  and 
0.004,  and  to  this  result  are  added  0.50.  Figures  obtained  by  this  calculation  are 
shown  in  columns  7  and  9.  In  columns  8  and  10  the  comparative  average  values 
show  that  up  to  an  inclination  of  15°  the  factor  0.004,  and  with  greater  angles 
the  factor  0.003,  give  the  best  results.  Therefore,  to  read  the  vertical  angle  'as 
accurately  as  possible,  the  Gradbogen  should  be  suspended  toward  the  higher  end 
of  the  cord  at  a  distance  from  the  center  obtained  by  multiplying  the  length  of 
the  cord,  at  angles  up  to  about  15°,  by  0.004  for  each  degree,  and  for  larger  angles 
by  0.003. 

"It  might  be  said  that,  in  the  deduction  of  this  rule,  the  weight  of  the  Grad- 
bogen and  the  tension  in  the  cord  have  not  been  considered.  But  when  two  sys- 
tems of  experiments  like  those  cited,  made  at  different  times  and  places,  and 
therefore  surely  under  very  different  circumstances,  gave  such  similar  results 
without  considering  the  above  factors,  we  are  hardly  justified  in  taking  them  into 
account. ' ' 

P.  &  E.  WITTSTOCK*  (communication  to  the  author):  We  read 
in  the  Engineering  and  Mining  Journal  of  January  16,  1897,  and 

*  Mathematical  instrument-makers,  Plan-ufer  92,  Berlin,  Germany. 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS.          137 

in  the  Colliery  Engineer  for  February,  1897,  descriptions  of  Mr. 
Scott's  new  mine  tachymeter,  which  so  recommended  itself  to  us 
that  we  at  once  undertook  its  construction.  In  the  meantime 
we  have  read  Mr.  Scott's  paper,  and  have  been  in  correspond- 
ence with  that  gentleman,  and  he  has  given  us  several  ideas 
concerning  this  latest  type  described  below ;  but  we  are  particu- 
larly indebted  to  him  for  suggestions  concerning  the  edge  gradu- 
ation for  the  vertical  circle  and  the  method  of  mounting  a  com- 
pass over  the  telescope,  to  take  the  place  of  the  striding  compass, 
which  has  not  yet  ceased  to  be  popular  in  this  country. 

The  extension  tripod  is  made  of  seasoned  maple,  is  of  a  light 
pattern,  and  closes  up  to  three  feet  in  length.  The  upper  ends 
of  the  legs  have  wooden  tongues  inserted  to  prevent  splitting. 
The  tripod  head  is  cast  in  one  piece,  and  the  connection  of  the 
instrument  is  established  by  a  strong  screw-thread  of  a  few 
turns.  This  is  as  simple  and  effective  as  is  possible,  and  pos- 
sesses the  advantage  of  never  getting  out  of  order. 

The  engineer,  who  has  to  work  occasionally  in  a  chilly  at- 
mosphere, will  appreciate  the  unusual  size  of  the  four  leveling 
screws.  Under  any  conditions  they  are  a  great  advantage  in 
connection  with  instruments  having  very  sensitive  levels. 

The  compound  vertical  axes  of  the  instrument  are  turned 
with  the  greatest  possible  precision,  are  fitted  to  each  other 
with  exacting  care,  and  are  of  such  strength  as  to  give  the 
whole  instrument  an  uncommon  rigidity  and  stability. 

Both  horizontal  and  vertical  circles  are  divided  on  solid 
silver.  The  figuring  on  the  horizontal  circle  runs  consecutively 
from  0  toward  the  right  around  to  359°  in  a  single  row.  That 
permits  the  opposite  verniers,  marked  I  and  II,  to  be  also 
single.  This  is  the  only  safe,  simple  and  systematic  method, 
as  the  angles  are  always  read  from  left  to  right,  no  matter  what 
the  size.  There  is  never  any  danger  of  reading  the  wrong  set 
of  figures  or  the  wrong  vernier,  as  might  happen  with  the 
double  row  of  figures  and  double  verniers,  which  were  devised 
in  the  mistaken  idea  of  being  better  adapted  to  suit  all  condi- 
tions. A  special  feature  of  our  graduation  is  its  remarkable 
exactness,  which  cannot  fail  to  give  satisfaction  to  the  most 
critical  and  scrutinizing  engineer.  The  figures  are  placed  un- 
usually close  to  the  edge  of  the  graduation,  which  fact  we  feel 
will  be  much  appreciated  by  those  who  have  experienced  the 


138         THE    EVOLUTION   OF    MINE-SURVEYING   INSTRUMENTS. 

difficulty  of  reading  the  point  of  contact  with  long  lines  and 
distant  figures. 

The  cylindrical  ends  of  the  horizontal  axis  rest  in  the  Y 
bearings  of  the  U-shaped  aluminum  standards.  The  bearings, 
one  of  them  adjustable,  have  the  usual  covers,  through  which 
are  inserted  the  friction  screws  with  ivory  points.  The  vertical 
pillars  terminate  in  screw-threads,  just  like  the  extremities  of 
the  horizontal  axes,  to  which  the  interchangeable  auxiliary  tele- 
scope and  its  counterpoise  weight  may  be  attached,  and  so  re- 
volved to  any  desired  position.  The  pillars  are  made  with 
large  openings,  and  of  such,  a  shape  (see  Fig.  89)  as  to  inter- 
fere as  little  as  possible  with  the  aiming  of  the  main  tele- 
scope. 

Both  telescopes  are  focused  by  a  rack  and  pinion  movement, 
and  protected  by  a  dust-guard  slide  that  is  not  cut  out  to  pro- 
vide for  the  objective-end  of  the  telescope  bubble  tube,  as  is 
very  often  done.  We  have  crowded  the  telescope  bubble  as 
near  to  the  ocular-end  as  possible  (see  Fig.  87),  in  order  to  ac- 
complish this  desirable  result.  In  this  position  it  is  equally 
effective,  and,  besides,  is  more  easily  observed  than  when  sus- 
pended exactly  below  the  middle  of  the  main  telescope.  All 
the  optical  parts  are  only  of  the  first  quality,  and  the  magnify- 
ing powers,  as  stated  in  the  following  table,  secure  for  the  field 
of  view  an  incomparable  brilliancy;  but,  whenever  we  are 
called  upon  to  employ  a  power  one-third  higher,  nothing  but 
satisfactory  results  are  still  obtained. 

On  one  end  of  the  horizontal  axis  is  the  vertical  circle ;  on 
the  other  the  gradienter  screw,  which  also  serves  as  the  verti- 
cal clamp-and-tangeiit-screw.  The  beveled  head  is  divided  into 
50  spaces,  each  of  which  corresponds  to  y^-  foot  at  a  distance 
of  100  feet;  or  if  the  screw  be  moved  through  two  entire  revo- 
lutions, the  horizontal  hair  of  the  diaphragm  will  travel  verti- 
cally over  the  space  of  1  foot,  100  feet  away. 

The  figures  placed  on  the  vertical  circle  divide  it  into  quad- 
rants running  each  way,  up  and  down,  from  the  central  zero- 
line.  In  this  way  an  angle  of  elevation  or  depression  may  be 
read  with  the  main  telescope  in  either  a  normal  or  a  reversed 
position.  Mr.  Scott  says,  in  his  estimation  it  is  better  to  check 
a  vertical  angle  by  reading  it  in  this  way  than  to  employ  oppo- 
site verniers,  which  increase  the  risk  of  ruining  the  graduations 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 


139 


by  the  grit  that  is  deposited  from  percolating  waters.  For 
this  reason  one  double  vernier  is  provided;  and  it  is  now 
placed  in  a  more  convenient  position  for  reading,  as  will  ap- 
pear shortly. 

Table  of  Dimensions. 

Sizes. 

Horizontal  circle, 

Vertical  circle, 

Main  telescope  (inverting), 

Magnifying  power,   . 

Object  glass,      .... 

Can  be  focused, 

Auxiliary  telescope  (inverting), 

Magnifying  power,    . 

Object  glass,     .... 

Can  be  focused, 

Length  of  needle,  compass  at- 
tachment, .... 

Weight  of  instrument  with  at- 
tachments, .... 


A. 

B-l. 

B-2. 

C. 

4  in. 

4£  in. 

5  in. 

5  in. 

4  in. 

4J  in. 

4£  in. 

5  in. 

7£  in. 

8  in. 

8  in. 

9£  in. 

18  diam. 

20  diam. 

20  diam. 

22  diam. 

1£  in. 

l|in. 

Hhi. 

l£in. 

down  to 

3  feet. 

5£  in. 

6  in. 

6  in. 

6£  in. 

12  diam. 

14  diam. 

14  diam. 

16  diam. 

fin. 

1  in. 

I  in. 

li  in. 

down  to 

3  feet. 

3f  in. 


3.58 


3f  in. 
3.95  kg.f 


The  only  difference  between  B-l  and  B-2,  as  appears,  is  in 
the  size  of  the  horizontal  circle.  In  B-l  the  verniers  are 
placed  on  the  top,  as  in  Fig  86 ;  while  in  B-2  they  occur  at  the 
side,  as  in  Fig.  87.  This  last  arrangement  gives  us  the  oppor- 
tunity of  placing  a  larger  and  more  delicate  bubble  on  the 
plates,  and  indeed  of  presenting  to  the  engineering  profession  a 
method  of  reading  and  illumination  which  cannot  be  surpassed. 
Its  special  advantages  may  be  enumerated  as  follows :  1.  It  is 
obvious  that  the  size  of  the  graduation  is  larger  without  in- 
creasing the  diameter  of  the  plates.  2.  The  verniers  can  be 
placed  at  any  angle  to  the  line  of  sight.  3.  The  plate  level 
may  occupy  its  normal  position,  and  need  not  be  cramped,  or 
made  to  extend  over  the  edge  of  the  plates  to  make  room  for 
the  vernier-openings.  4.  The  diffusion  of  bright  sunlight,  or 
of  artificial  light  underground,  is  more  agreeable  to  the  eye. 
5.  When  not  in  use  the  reflector-shades  are  to  be  closed  up,  to 
protect  the  vernier. 

Having  given  above  a  brief  general  description  of  the  four 
types  as  we  make  them,  we  desire  now  to  dwell  in  detail  upon 
some  of  the  more  characteristic  features  of  this  new  design, 
which  we  do  not  hesitate  to  say  gives  us  the  right  and  privilege 


*  7.89  Ibs. 


t  8.71  Ibs. 


140         THE    EVOLUTION   OF    MINE-SURVEYING    INSTRUMENTS. 

to  denominate  Scott's  mine  tachymeter  the  most  universally 
convenient  and  complete  instrument  ever  constructed  for  mines. 


FIG.  86. 


Scott's  Mine  Tachymeter,  P.  &  E.  Wittstock's  Size  A  (4  in.). 

The    Interchangeable    Auxiliary  Telescope. — In    America    the 
auxiliary  telescope  has  been  in  use  for  a  great  many  years,  but 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


141 


never  before  has  it  been  possible  to  use  it  in  more  than  one 
position  as  the  case  might  require.     But  here  is  an  appliance 


FIG.  87. 


Scott's  Mine  Tachy meter,  P.  &  K.  Wittstock's  Size  B-2  (5  in.). 

which  can  be  used  on  the  top,  if  a  horizontal  angle  is  to  be  read 
while  the  telescope  is  steeply  inclined,  or  at  the  side,  if  an  un- 


142         THE    EVOLUTION   OF    MINE-SURVEYING    INSTRUMENTS. 

usually  steep  vertical  angle  is  to  be  read ;  and  in  each  case  with 
positively  no  correction  for  eccentricity.  It  may  be  attached 
as  desired  to  any  one  of  the  four  radial  arms  of  the  main  tele- 
scope, and  ranged  very  quickly  and  accurately  into  perfect 
adjustment  with  it  by  two  opposing  thumb-screws,  as  shown 
in  all  of  our  illustrations.  This  adjustment  for  alignment  is 
secured  in  a  moment  by  sighting  the  main  telescope  at  a  dis- 
tant light  and  bringing  the  auxiliary  to  bear  on  the  same  light. 
The  necessity  for  any  adjustment  for  absolute  parallelism  is 
now  entirely  done  away  with;  because  in  reading  vertical 
angles  it  is  used  only  at  the  side,  and  in  reading  a  horizontal 
angle  at  one  of  whose  sides  the  telescope  dips  very  low  below 
the  horizon,  it  is  attached  only  at  the  top. 

The  Vertical  Circle. — Generally  it  will  be  customary  to  use  the 
auxiliary  at  the  right  side,  opposite  to  the  vertical  circle;  but 
if  it  should  ever  be  found  more  convenient  to  attach  it  to  the 
left  side,  as  shown  in  Figs.  87  and  89,  the  edge  graduation 
will  never  be  found  to  conflict  with  the  auxiliary  so  placed. 
But  the  most  desirable  point  which  Mr.  Scott  wished  to  develop 
here  has  reference  to  occupying  a  very  cramped  position  in 
surveying  a  narrow  and  precipitous  inclined  shaft.  The  engi- 
neer in  such  a  case  may  now  make  an  observation  through 
either  of  his  telescopes,  and  read  both  the  horizontal  and  verti- 
cal circles  without  moving  in  his  tracks  !  The  double  vernier 
is  carried  by  an  aluminum  frame,  with  ample  means  of  adjust- 
ment, that  protects  the  whole  circle,  and  is  placed  in  a  con- 
venient position  at  about  45°  above  the  horizon.  The  opening 
is  covered  by  a  glass  plate  of  a  curvature  corresponding  to  that 
of  the  circle,  as  is  indeed  the  case  with  the  verniers  of  the 
horizontal  circle  shown  in  Fig.  87. 

Disappearing  Stadia  Webs. — When  the  diaphragm  is  made  of 
extra  thickness,  and  the  cross  and  stadia-webs  are  mounted  on 
opposite  sides,  so  that  each  group  may  be  focused  separately 
with  the  ocular,  it  seems  impossible  to  us  to  employ  equally 
high  telescopic  powers  satisfactorily  in  such  limited  dimensions 
as  are  usual  in  the  ordinary  size  surveying  instruments.  If, 
for  instance,  the  focus  of  the  objective  is  9  inches,  and  the 
telescope  of  20  diameters  power,  then  the  focus  of  the  first  lens 

9x2        9 
in  the  ocular  will  be     9      —       inch,  and  the  distance  of  the 


THE    EVOLUTION   OF    MINE-SURVEYING   INSTRUMENTS.          143 
9  9 

image  from  the  first  lens  ==  ^.  inch.     Consequently 

the  thickness  of  the  diaphragm  must  not  be  greater  than  j^ 
inch,  in  order  to  leave  a  little  space  between  the  eye-piece  and 

FIG.  88. 


Scott's  Tachymeter  with  Fixed  Compass,  made  by  P.  &  E.  Wittstock. 

diaphragm  when  the  webs  on  the  further  side  are  in  focus. 
Now,  where  is  the  room  that  should  be  allowed  to  suit  the 
varying  requirements  of  the  eyes  of  different  operators?  Further 
than  this,  in  such  a  case  the  webs  that  are  out  of  focus  are  not 
far  enough  away  to  be  entirely  invisible,  but  blur  the  field  of 


144 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS. 


view;  and,  besides,  every  time  it  is  desirable  to  change  from 
one  set  of  webs  to  the  other  it  is  necessary  to  re-focus  not  only 
the  ocular,  but  also  the  objective. 

Our  construction  provides  for  the  usual  worm-thread  focus- 
ing arrangement  for  the  ocular,  with  ample  play  to  suit  the  re- 
quirements of  different  eyes.  The  cross-webs  are  also  mounted 


FIG.  89. 


J 


Detachable  Aluminum  Compass,  on  Scott's  Mine  Tachymeter,  made  by  P.  &  K. 

Wittstock. 

in  the  usual  manner  on  a  diaphragm  of  the  usual  form  and  size. 
It  has,  however,  a  tube-like  prolongation  toward  the  objective, 
in  which  a  second  diaphragm  moves  that  carries  the  stadia- 
webs.  By  moving  this  second  diaphragm  backward  or  forward, 
the  stadia-webs  are  brought  into  the  field  of  view,  or  moved 
entirely  out  of  it.  The  screws  which  govern  this  motion  from 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS.          145 

the  outside  are  of  ample  capacity  to  do  this  effectively.  It  will 
be  understood  that  by  this  arrangement  the  cross-webs  are 
never  out  of  focus,  and  the  adjustment  of  the  line  of  collimation 
is,  therefore,  never,  impaired;  since  the  eye-piece  and  object- 
glass  always  remain  untouched. 

Luminous  Levels. — We  have  experimented  considerably  with 
luminous  levels,  and  believe  we  have  the  honor  to  be  the  first 
house  actually  to  introduce  them  as  suggested  by  Mr.  Scott.  We 
have  found  that  when  exposed  to  a  diffused  dry  light  the  lumin- 
ous substance  will  act  longest  and  best,  and  in  the  dark  the  divis- 
ions in  the  glass  and  the  bubble  itself  appear  quite  distinct. 
When  the  action  becomes  weaker,  and  the  luminosity  fainter, 
it  is  with  some  difficulty  that  the  bubble  can  be  detected  even 
with  a  magnifier ;  but  the  efficiency  in  this  respect  is  restored 
by  burning  a  strip  of  magnesium  before  the  bubbles.  However, 
it  is  only  on  rare  occasions  that  this  novelty  will  be  an  actual 
necessity,  as  Mr.  Scott  says,  and  no  doubt  what  we  have  ac- 
complished will  amply  suit  all  requirements. 

The  Compass  Attachment. — To  adapt  this  instrument  to  all  the 
requirements  as  demanded  still  in  Germany,  England,  and  else- 
where, a  circular  compass-box,  made  of  aluminum,  is  mounted 
on  the  upper  vertical  pillar,  in  the  same  way  as  the  auxiliary 
telescope  is  attached.  Most  mine  surveyors  will  have  established 
near  their  works  a  true  meridian  determined  by  astronomical 
observation.  The  instrument  should  be  set  up  at  one  end  of 
this  line,  and,  when  the  other  is  sighted  through  the  telescope, 
the  needle  is  brought  to  read  upon  the  north  point  by  means  of 
the  opposing  milled-head  screws  below.  By  this  same  means 
any  desired  declination  can  be  set  off.  As  the  compass-box  is 
very  light,  weighing  only  .15  kg.,  or  5  ounces,  there  is  no  rea- 
son why  observations  through  the  main  telescope  should  not  be 
made  at  any  considerable  inclination  with  the  compass  still 
attached  and  the  needle  clamped ;  but  before  the  needle  is  read, 
of  course,  the  telescope  must  be  brought  back  to  a  horizontal 
position.  We  also  make  a  non-adjustable  style,  as  shown  in 
Fig.  89,  which  can  be  very  easily  and  exactly  attached,  and  can 
be  carried  in  the  pocket.  Of  course,  there  is  no  limit  to  the 
length  of  needle  that  may  be  used  in  this  model,  but  we  recom- 
mend those  suggested  in  the  table. 


146         THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 

EDWIN  J.  HULBERT*  (communication  to  author) :  I  have  been 
reading  with  much  interest  your  able  article  in  which  (Fig.  31) 
you  have  included  a  description  of  an  instrument  which  evi- 
dently you  did  not  know  was  designed  by  the  writer  in  1854  to 
conduct  surveys  in  the  old  Cliff  mine  on  Keweenaw  Point.  The 
instrument  was  designed  for  the  execution  of  a  certain  problem, 
and  did  it  effectively  and  satisfactorily,  though  there  may  be 
means  now  in  this  progressive  age  still  more  accurate  and  rapid. 
I  have  fought  my  fight  in  the  battle  of  life,  and  seek  not  for 
more  recognition  from  the  world  than  has  been  thus  far  observ- 
able; for  be  one  an  explorer,  discoverer,  scientist,  historian, 
poet  or  author,  he  is  bound  later  on  by  some  investigator  to  be 
effectively  "  smashed."  Iconoclasm  is  an  attractive  diversion, 
and  will  ever  be  in  fashion  •  of  course,  there  are  some  bugs 
larger  than  others,  but  each  and  every  one  remains  still  a  bug. 

It  should  be  borne  in  mind  in  examining  the  problem  I  had 
confronting  me  that  in  the  early  days  the  phenomenal  deposits 
of  native  copper,  without  precedent  in  the  history  of  mining, 
were  looked  upon  with  much  doubt  as  to  their  persistency  in 
depth.  Capital  was  not  abundant — in  most  cases  insufficient—- 
skilled labor  wanting,  and,  therefore,  extreme  economy  en- 
joined. In  fact,  mining  in  the  two  decades  following  1845 
should  be  considered  to  have  been  explorative  rather  than 
exploitative ;  the  shafts  and  drifts  usually  being  small  and 
cramped.  Shafts  were  not  sunk  by  an  engineer's  lines  for  a 
direct  and  regular  course,  nor  for  any  particular  grade,  but 
followed  the  sinuosities  of  the  footwall.  The  surveyor  was 
forced  to  adapt  himself  to  the  exigencies  presented  by  the  rude 
bed-planking  in  the  undulating  shafts  upon  which  the  kibbalsf 
slid  to  and  from  the  different  levels.  Upon  this  no  elaborate 
stations  could  be  erected,  and  his  almost  invariable  accompani- 


*  Ketired  mining  engineer,  a  pioneer  in  the  Lake  Superior  district,  who  dis- 
covered the  celebrated  Calumet  copper  lode  on  August  27,  1864 ;  now  residing  at 
Via  Nomentana  257,  Kome,  Italy. 

f  Kibbal.  (A  bucket  or  little  tub.  Armoric.  Quibell,  idem.}  A  bucket  in 
which  all  work  or  ore  is  raised  out  of  the  mines.  Gear  barrels  in  the  North  of 
England.  A  whym-kibbal  is  a  larger  one,  which  belongs  to  the  machine  called 
a  whym,  and  serves  to  draw  water  with,  or  bring  up  the  ore  to  grass.  Some  of 
these  larger  barrels  or  kibbals  contain  120  gallons  when  they  are  intended  for 
drawing  up  water  out  of  the  mines.  (Glossary.  Pryce,  Mineralogia  Cornubiensis, 
London,  1778.)  Written  also  "  Kibble." 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS.          147 

ments  were  smoke,  foul  air  and  precarious  surroundings.  Con- 
venient and  proper  instruments  were  not  at  his  command,  and 
in  fact,  the  necessity  for  the  skill  of  a  mining  engineer  was 
looked  upon  askance,  and  generally  he  was  regarded  by  the 
miners  as  a  genteel  supernumerary. 

In  those  early  days,  mining  captains  and  skilled  labor  for 
drift  work,  for  shaft  and  gallery  timbering,  and  for  setting  of 
pumps  and  of  hoisting-engines  were  brought  from  Cornwall ; 
many  of  the  captains  bringing  with  them  the  ordinary  compass- 
dial,  depending  upon  the  polarity  of  the  needle  for  direction 
and  for  repeating  upon  the  suriace  a  duplication  of  the  tangents 
taken  in  the  underground  work.  Seldom,  if  ever,  was  a  back 
sight  taken  to  test  for  magnetic  variation.  Where  a  pump, 
iron  railways  or  other  masses  of  iron  occurred,  their  size  and 
distance  from  the  compass  wrere  very  carefully  measured,  and 
upon  the  surface  repetition  similar  pieces  were  placed.  ~No 
triangular  calculated  work  was  attempted.  Inclinations  in  the 
shafts  were  taken  by  means  of  the  plumb-line,  and  hoiizontal 
offsets  and  measurements  made  with  linen  tapes,  the  age  of 
which  was  not  often  questioned. 

It  was  evident  to  me,  that,  in  order  to  carry  down  a  base 
through  these  cramped  and  irregular  shafts,  and  from  it  to  pro- 
ject a  tortuous  traverse  many  times  its  length,  no  accuracy  could 
be  obtained  by  use  of  the  above  enumerated  means.  The 
polarity  of  the  needle  upon  or  within  these  Lake  Superior 
rocks  was  not  to  be  trusted  in  the  least  degree;  for,  as  the 
electric  currents  following  either  wall  of  the  vein  varied  in 
force,  the  deflection  also  varied  according  to  the  distance  of  the 
instrument  from  it.  The  Cliff  mine  fissure-vein  had  a  dip  to 
the  eastward  varying  from  83  to  86  degrees ;  consequently  no 
sight  on  this  inclination  could  be  taken  with  the  ordinary  transit 
telescope. 

Before  designing  an  instrument  suitable  for  this  survey, 
some  experiments  had  to  be  made.  Having  at  hand  a  rude 
half-circumferentor,  or  goniometer,  carrying  the  ordinary  slit 
compass-sights,  I  attached  to  the  side,  overhanging  the  tripod, 
a  half-circle  made  of  wood,  graduated  with  a  penknife,  and 
provided  also  with  slit  sights.  Beginning  on  the  surface,  with 
the  upper  main  sights  bearing  upon  the  base-line  of  the  trian- 

11 


148 


THE    EVOLUTION  OF    MINE-SURVEYING   INSTRUMENTS. 


FIG.  90. 


gulation,  I  took  the  inclination  with  the  side  sights  directed 
towards  a  candle  in  the  mine  level  below.  Then  I  erected  the 
instrument  upon  the  point  occupied  by  the  candle,  and  with 
the  two  sights  clamped  in  the  position  read  at  the  surface, 
back-sighted  to  the  surface  point;  and  so  established  a  line 
underground  parallel  (or  as  nearly  parallel  as  it  was  possible 
for  this  improvised  wooden  model  to  make  it)  with  the  base- 
line of  the  surface  triangulation.  Repeating  the  work  several 
times,  making  mechanical  corrections  for  instrumental  imper- 
fections, I  found  the  results 
fairly  satisfactory;  and  being 
satisfied  that  with  care  in  the 
manipulation  of  a  good  instru- 
ment of  like  nature  good  work 
could  be  done,I  completed  the 
design  of  the  "  double  tele- 
scope transit "  (Fig.  90)  with- 
out the  special  interjection  of 
French  influences  presup- 
posed by  you.  The  plans  I 
laid  before  Mr.  Young,  of 
Philadelphia,  personally,  and 
he  stamped  them  with  his 
approval. 

At  that  same  visit,  I  think 
in  1854,  I  showed  him  my 
sketch  of  a  transit  with  a 
base  in  the  form  of  a  horse- 
shoe mounted  upon  three 
leveling  screws  and  an  open- 
topped  tripod-head,  to  be 
used  for  vertical  sighting  or  for  slight  deviations  therefrom ; 
also  another  sketch  of  a  transit  with  hinged  standards,  so  that 
the  telescope  could  be  swung  forward  beyond  the  interference 
of  the  plates.  These  last  two  projects  were  rejected  by  this 
venerable  mechanic ;  for  he  believed  that  he  could  not  provide 
against  the  spreading  of  the  horseshoe  base,  or  construct  a 
hinged  standard  so  perfectly  that  it  would  always  project  a  line 
twice  alike.  Mr.  "Walter  Crafts,  then  superintendent  of  the  old 


Hulbert's  Transit,  the  "Lake  Superior 
Pattern"  of  Fig.  31. 


THE    EVOLUTION  OF    MINE-SURVEYING    INSTRUMENTS.          149 

St.  Mary's  mine,  but  now  of  Columbus,  0.,*  I  think,  saw  my 
drawings  of  the  horseshoe  transit.  At  any  rate,  the  proposition 
for  a  design  similar  to  Fig.  64  was  extant  nearly  twenty  years 
before  Buff  &  Berger  built  that  one  for  Mr.  G.  H.  Crafts.  The 
elder  Young,  now  deceased,  thought  he  could  not,  as  I  say, 
insure  the  absolute  stability  of  the  adjustments  of  either  of 
these  models. 

In  all  my  experience  I  have  always  discredited  the  efficiency 
of  plumb-lines  in  shafts  of  any  considerable  depth,  believing 
that  greater  accuracy  could  be  obtained  by  a  sight  through  a 
telescope  adjusted  to  the  nadir.  After  "  holing "  through  to 
the  Howe-shaft  at  the  Cliff  mine,  I  tried  to  close  the  survey  in- 
strumentally  by  dropping  plumb-lines  630  feet  in  length.  The 
plummet  was  suspended  successively  in  water,  molasses  and 
diluted  tar.  The  air  currents  were  then  entirely  cut  off,  but, 
after  several  hours'  waiting,  in  each  instance  the  lines  had  not 
assumed  absolute  rest.  We  next  tried  the  falling  of  a  well- 
turned  plummet  from  the  top  of  the  shaft  to  its  bottom,  where 
we  placed  a  bed  of  clay  to  receive  the  impression.  In  several 
trials,  however,  we  did  not  succeed  in  getting  it  to  drop  twice  in 
exactly  the  same  spot,  although  we  burned  off  the  thread  that 
held  it  at  the  surface.  But  with  the  instrument  (Fig.  31  or 
Fig.  90)  very  carefully  leveled,  and  sighting  down  repeatedly 
with  the  zero  of  the  limb  turned  respectively  to  the  four  car- 
dinal points  of  the  circle,  we  found  the  four  points  thus  estab- 
lished to  coincide  very  nearly.  I  do  not  believe  that  a  plumb- 
line  of  any  considerable  length  is  going  to  obey  the  desire  of  the 
engineer  so  far  as  to  vibrate  precisely  in  any  one  direction ;  and 
I  fancy  that  should  Dr.  Schmidt's  apparatus  (Fig.  27)  be  opened 
out  from  the  plumb-line  after  it  was  supposed  to  have  come  to 
rest,  it  would  begin  of  itself  to  renew  its  oscillations  along  di- 
rections governed  apparently  by  no  fixed  rule. 

I  should  place  more  reliance  upon  a  downward  sight  through 
a  properly  constructed  and  accurately  adjusted  telescope  than 
in  the  repose  of  a  plumb-line.  We  trust  the  telescope  for  the 

*  SECRETARY'S  NOTE.— Walter  Crafts,  born  1839,  graduated  C.E.  at  Troy  in 
1859  ;  studied  at  Freiberg  in  1861-62  ;  afterwards  went  to  Lake  Superior  ;  lived 
several  years  at  Columbus  ;  and  died  August  2,  1896.  For  these  facts  I  am  in- 
debted to  Mr.  B.  S.  Lyman  of  Philadelphia,  Pa.— K.  W.  K. 


150 


THE    EVOLUTION    OF    MINE-SURVEYING    INSTRUMENTS. 


FIG.  91. 


measurement  of  all  horizontal  distances,  and  we  never  question 
its  accuracy  in  taking  inclined  angles  and  observations ;  now, 
therefore,  why  not  accord  it  the  same  confidence  in  taking  a 
truly  vertical  sight  ?  Except  for  moderately  short  distances,  I 
always  considered  the  plumb-line  a  positive  nuisance,  a  con- 
sumer of  time  and  a  disagreeable  tester  of  patience. 

The  survey  for  which  the  instrument  in  question  was  made 
was  one  in  which  cross-cuts  from  the  30-,  40-,  60-  and  70-fathom 
levels  had  to  be  driven  back  to  the  position  of  Avery-shaft 
(vertical),  where  we  had  seven  gangs  of  miners,  before  the  work 

was  finished,  raising  and  sink- 
ing against  one  another, — with 
an  ultimate  error  of  but  4 
inches.  That  may  be  consid- 
ered very  reasonably  close, 
when  mud,  slime,  smoke  and 
careless,  ignorant  assistants 
are  given  their  place  in  the 
conditions  that  militate  against 
one's  chances  for  success. 

In  a  second  survey,  involv- 
ing a  traverse  of  nearly  a 
quarter  of  a  mile,  the  error 
in  closing  was  about  3  feet, — 
not  quite  so  successful;  but 
one  cannot  hit  a  bull's  eye 
every  time,  even  under  the 
most  favorable  circumstances. 
Put  a  "  newly-fledged  chick- 
en "  from  the  Michigan  Col- 

Hulbert's  Original  Side-Telescope          ,  „     ,T.  .  , 

Transit  lege     of     Mines     into     such 

shafts    as   we    had   on   Lake 

Superior  forty  years  ago,  and  I  fancy  he  would  be  very  careful 
how  he  handled  his  few  trumps. 

It  is  particularly  fitting  to  remark  here,  in  this  contribution 
to  your  paper  on  the  evolution  of  mining  instruments,  upon 
how  my  second  design  was  evolved  from  this  first  parental  in- 
strument. In  1856  we  were  making  ready  to  "  hole  "  into  the 
Howe  shaft  of  the  Cliff  mine  at  the  60-fathom  level,  and  for  this 


THE    EVOLUTION    OF    MINE-SURVEYING    INSTRUMENTS.         151 

special  piece  of  work,  in  that  year  I  designed,  and  had  Young 
make  for  me,  what  was,  to  the  best  of  my  knowledge  and  be- 
lief, the  first  application  of  the  side  auxiliary  telescope.  It  is 
reproduced  here  in  Fig.  91  from  a  photograph  preserved  and 
kindly  loaned  by  Mr.  Young,  and  represents  the  ordinary  flat- 
center  transit  instrument  of  that  day  with  the  second  telescope 
mounted  at  the  side.  The  tripod  legs,  as  was  then  general, 
were  of  solid  rigid  pieces ;  though  we  had  those  in  use  con- 
structed of  three  brass  tubes  sliding  one  within  the  other.  The 
shifting  tripod-head  was  also  made  at  my  suggestion  by  Young, 
who  reaped  the  pecuniary  benefit  of  its  well-merited  subsequent 
popularity.  I  never  occupied  myself  with  the  idea  of  patent 
right  and  profit,  as  you  assure  me  has  been  the  case  with  yourself. 

The  method  of  mounting  the  auxiliary  telescope  prostrate 
upon  the  vertical  circle  was  very  similar  to  that  pursued  in  my 
first  instrument  (Fig.  90),  except  that  it  was  removed  just  far 
enough  to  escape  the  edge  of  the  plates.  But  the  combination 
was  mounted  now  in  a  more  stable  position  at  one  extremity, 
and  concentrically  with  the  axis  of  revolution. 

I  suppose,  in  the  ethics  of  instrumental  construction  to-day, 
it  would  be  considered  necessary  to  counterbalance  with  a 
weight  opposite,  or  at  least  to  put  the  vertical  circle  at  one  side 
and  the  auxiliary  telescope  at  the  other;  but  we  could  not 
arrive  at  absolute  perfection  at  once  and  leave  nothing  for  pos- 
terity to  accomplish. 

With  the  improvement  of  the  original  instrument,  however, 
as  now  accomplished  by  you  in  the  "  Scott  tachymeter,"  in  its 
solidity  and  perfect  construction,  the  engineer  should  be  quite 
content  to  undertake  the  solution  of  the  most  difficult  problem 
ever  presented  in  the  mine. 


152          THE    EVOLUTION    OF    MINE-SURVEYING    INSTRUMENTS. 


The  Evolution  of  Mine-Surveying  Instruments. 

BY  DUNBAR  D.    SCOTT,    HOUGHTON,   MICH. 
(See  Trans.,  xxviii.,  679;  xxix.,  931.) 

CONTINUED  DISCUSSION. 

ALFRED  C.  YOUNG*  (communication  to  the  Secretary):  Before 
the  appearance  of  Mr.  Scott's  paper  in  these  Transactions  we 
were  not  specially  interested  in  the  investigation  which  he 
has  started ;  but  at  his  request  we  have  endeavored  to  collect 
from  musty  records  and  the  recollection  of  our  old  friends  a 
brief  chronicle  of  the  progress  made  by  this  house. 

As  3000  instruments  were  manufactured  by  us  before  any 
descriptive  record  was  kept,  and  2000  more  before  the  record 
contained  more  than  a  statement  whether  the  instrument  was 
a  transit  or  a  level,  and  sometimes  its  size,  we  approach  the 
task  with  timidity,  trusting  that  the  reader  will  bear  the  diffi- 
culties in  mind,  particularly  as  the  writer's  predecessors,  from 
whom,  no  doubt,  the  information  desired  could  have  been 
obtained,  have  passed  away. 

Instruments  for  surveying  were  manufactured  by  David 
Bittenhouse,  of  Philadelphia,  as  early  as  1760 ;  but  it  was  not 
until  late  in  the  first  quarter  of  this  century  that  there  was  any 
American  market  for  an  instrument  outside  of  the  ordinary 
surveyor's  compass.  "With  the  advent  of  canals  and  railroads, 
and  the  more  extensive  development  of  the  Pennsylvania  coal- 
fields, arose  a  demand  for  surveying-instruments  to  meet  prob- 
lems in  engineering  beyond  the  limited  field  of  the  compass. 

On  May  1,  1820,  in  which  year  the  practical  mining  of 
anthracite  coal  in  Pennsylvania  began,  William  J.  Young,  who 
had  served  his  apprenticeship  with  one  Thomas  Whitney, 
started  in  business  on  Dock  Street,  in  Philadelphia.  Recogniz- 
ing the  fact  that  compasses,  or  "  circumferentors,"  as  they  were 

*  Conducting  the  establishment  of  Young  &  Sons,  Philadelphia,  Pa. 


THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS.          153 

commonly  called,  were  not  equal  to  the  demands  made  upon 
them,  and  that  the  English  theodolites  had  too  many  parts 
liable  to  injury,  were  cumbersome  and  ill-adapted  to  trans- 
portation, Mr.  Young  commenced  to  plan  an  instrument  that 
would  permit  horizontal  angles  to  be  taken  independently  of 
the  needle,  and  allow  "  back-sights "  to  be  obtained  without 
reversing  the  telescope  in  its  bearings. 

In  1831  he  introduced  the  first  "American  engineer's  transit" 
(Fig.  60*  of  Mr.  Scott's  article).  From  that  time  to  the 
present  all  improvements  have  been  merely  in  the  perfecting 
of  details  and  the  addition  of  attachments  to  meet  special  re- 
quirements— so  well  were  the  fundamental  principles  thought 
out  by  the  inventor,  even  to  such  minor  features  as  the  placing 
of  the  verniers  at  one  side  of  the  standards,  so  as  not  to  risk 
disturbance  of  the  instrument  while  readings  were  taken. 

In  July,  1858,  he  patented  the  "  shifting-tripod-head."  On 
simply  loosening  the  leveling-screws,  the  transit  can  be  shifted 
a  short  distance  in  any  direction  after  the  instrument  has  been 
approximately  set  up.  No  improvement  has  been  made  in 
this  invention  since  its  introduction. 

The  first  compound  "  long-center  "  transit  was  made  for  J. 
Simpson  Africa,  Esq.,  President  of  the  Union  Trust  Company 
of  this  city,  who,  in  a  letter  dated  February  1st,  1899,  says  : 

* '  I  am  reminded  that  the  first  long-center  transit-instrument  mentioned  in  your 
books  was  purchased  by  me  November  11,  1853. 

"  My  engineering  records  and  papers  being  at  my  old  home  (Huntingdon, 
Pa. ),  the  only  information  I  can  give  now  is  from  recollection.  Through  my 
instructor  in  practical  engineering,  Mr.  Samuel  W.  Mifflin,  I  made  the  acquaint- 
ance of  Mr.  William  J.  Young,  the  founder  of  your  house.  One  of  my  duties 
was  to  test,  in  actual  surveys,  transits  that  he  had  made  for  a  railroad  then  in 
progress  of  construction.  All  these  had  short  reversible  telescopes,  and  verniers 
for  the  plates  were  within  the  compass-box. 

' l  Needing  in  my  own  business  an  instrument  with  which  I  could  measure  angles 
with  greater  precision  than  could  be  attained  by  those  mentioned  above,  I  sug- 
gested to  Mr.  Young  to  construct  for  me  a  theodolite  somewhat  after  the  English 
model.  He  convinced  me  that  a  transit  with  a  long  center,  wider  plates  than  were 
commonly  used,  verniers  outside  the  needle-box,  and  a  long  telescope,  would  meet 
my  requirements,  and  be  more  satisfactory  than  a  theodolite.  This  conference 
resulted  in  my  giving  him  an  order  for  the  instrument  you  mentioned. 

' '  I  used  it  with  great  pleasure  and  satisfaction  for  many  years  in  general  engi- 
neering work,  and  especially  in  the  laying-out  of  towns,  and  in  denning  disputed 
boundaries,  where  the  greatest  attainable  accuracy  was  desired.  Many  years  later 

.*  Page  66. 


154        THE    EVOLUTION    OF    MINE-SURVEYING    INSTRUMENTS. 

I  had  another  transit  made  at  your  establishment,  built  on  the  same  general  plan 
with  the  then  modern  improvements  added.  This  instrument  took  the  place  of 
the  one  made  in  1853,  and  is  now  in  use  by  one  of  my  sons." 

As  to  the  dates  of  the  introduction  of  the  various  forms  of 
mining  attachments  to  engineers'  transits,  and  the  names  of 
those  who  suggested  these  improvements,  our  early  records 
supply  but  meager  information.  Fortunately,  however,  some 
of  the  instruments  are  still  in  existence,  from  which  photo- 

FIG.  92. 


Bartelot's  Mining  Compass. 

graphs  have  been  obtained,  leaving  in  doubt  only  to  whom  the 
honors  may  belong.  The  following  list  comprises  mining  in- 
struments made  by  this  house  at  various  times,  and  not  hitherto 
mentioned  in  this  discussion. 

Fig.  92  (our  shop  !N"o.  3366)  represents  an  instrument  made 
in  April,  1855,  for  a  Dr.  Bartelot,  who  seems  to  have  lived  in 
the  anthracite  coal  regions  of  Pennsylvania.  The  instrument 
was  intended  only  for  magnetic  surveys,  so  that  the  compass- 
box  was  placed  conspicuously  above,  w^here  observations  of  the 
needle  would  be  least  obstructed.  The  compass  was  provided 


THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS. 


155 


FIG.  93. 


with  what  was  then  known  as  a  "  Nonius-plate  " — a  simple 
marginal  indicator  that  marked  off  the  degrees,  and  the  larger 
subdivisions  thereof,  to  be  used  in  allowing  for  variation.  I 
suppose  Pedro  Nunez,  the  Portuguese  mathematician,  who 
lived  in  the  first  half  of  the  sixteenth  century,  was  the  first  to 
use  this  device,  but  Bittenhouse  is  said  to  have  been  the  first  to 
use  the  vernier  for  this  purpose.  The  complete  revolution  of 
a  telescope  in  a  design  of  this  peculiar  kind  was  impossible  ; 
and  the  method  resorted  to,  of  using  duplex  telescopes  for 
forward-  and  back-sighting,  makes  this 
model,  so  far  as  we  know,  unique  among 
mine-surveying  instruments.  The  only 
other  type  at  all  similar  is  Mr.  Hoskold's 
(Fig.  39*),  which  he  was  perfecting  some 
two  years  later ;  but  the  methods  employed 
in  each  case  will  scarcely  permit  a  com- 
parison. The  duplex  telescopes  revolved 
about  20°  from  the  horizon  each  way, 
upon  a  common  axis,  that  could  be  ad- 
justed for  horizontality  by  means  of  the 
capstan-head  screws  shown  in  the  figure 
just  below  the  base  of  the  standards;  but 
their  adjustment  for  parallelism  could 
only  be  secured  by  the  maker.  The  in- 
strument was  leveled  by  the  ball-and- 
socket  base,  the  four  leveling-screws  and 
the  box-bubble  at  the  side  of  the  compass- 

Mulloney's  Mining  Dial. 

Fig.  93  (our  shop  No.  3448)  represents 

a  mining  instrument  made  in  October,  1855,  for  J.  F.  Mulloney. 
It  is  decidedly  of  English  parentage,  possessing  the  same  rack- 
movement  shown  in  Fig.  16,f  and  an  arch  much  as  it  appears 
in  Fig.  15.J  The  horizontal  plates  were  maneuvered  by  the 
same  kind  of  rack-work.  But  the  most  remarkable  feature  is 
the  substitution  of  "  Locke's  sights  "  for  the  telescope.  These 
sights  are  practically  what  are  known  to-day  as  Locke's  hand- 
level,  invented  by  Prof.  John  Locke,  M.D.,  of  Cincinnati,  in 
1850.  I  suppose  Mr.  Mulloney  wished  to  use  the  sights  for 


*  Page  44. 


f  Page  18. 


t  Page  17. 


156        THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS. 

leveling  purposes,  and,  as  they  did  not  permit  accurate  cen- 
tering, he  very  wisely  demanded  that  the  arch  be  graduated 
and  read  by  a  simple  index  to  only  J°.  The  base  of  this  in- 
strument is  very  tall,  slender,  and  really  an  ill-proportioned 
type,  though  it  was  very  common  in  those  days.  From  the 
ball  there  extended  down  through  the  barrel  a  square  shank, 
upon  the  faces  of  which  worked  the  opposing  screws  shown 

FIG.  94. 


The  Smith-Hedley  Dial. 

just  above  the  tripod  head.  After  clamping  the  ball  and 
socket  tightly,  the  instrument  could  be  brought  to  a  more 
perfect  level  by  use  of  these  screws.  Two  extra  tripods  with 
sockets  for  holding  candles,  as  is  common  in  Cornwall  to-day, 
were  furnished  with  this  instrument. 

Fig.  94  (our  shop  No.  3545)  represents  a  modification  of  the 
Hedley  dial,  made  in  October,   1855,  for  Thomas  Smith,  of 


THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS.          157 


FIG.  95. 


Luzerne  county,  Pa.,  and  bears  the  distinction,  we  believe,  of 
being  the  first  Hedley  dial  ever  provided  with  a  telescope,  Mr. 
Stanley's  instrument  (Fig.  40*)  not  being  made  until  1874. 
The  Smith-Hedley  dial  had  within  the  compass-box  a  horizontal 
plate,  graduated  to  read  minutes,  that  was  governed  in  its 
movements  also  by  rack-work.  The  rocking  limb  was  10  in. 
long  and  provided  with  a  side  arc  upon  which  grades  as  great 
as  70°  could  be  observed  before  the  limb  came  in  contact  with 
the  base.  In  this  particular,  this  style  of  base  or  support  is 
superior  to  the  Hoffman-Harden  tripod-head  used  by  Mr.  Stan- 
ley, until  he  remodeled  the  rocking  limb  (Fig.  63f),  so  as  to 
permit  vertical  sights.  How- 
ever, these  instruments  are 
out  of  date  now  in  this  coun- 
try, though  there  was  a  time 
when  they  were  widely  used 
in  railroad  construction.  It 
is  from  this  instrument  that 
compasses  designed  to  give 
horizontal  angles  independ- 
ently of  the  magnetic  needle 
received,  and  still  bear,  the 
name  "  railroad  compasses." 

It  was  but  a  step  in  the  line 
of  progress  to  mount  the  tele- 
scope in  Y's,  as  shown  in  Fig.  95,  and  attach  it  to  the  instru- 
ment shown  by  Mr.  Scott  in  Fig.  34.  J  We  believe  that  this 
was  the  first  American  top-auxiliary  telescope,  and  that  the 
opinion  ascribed  to  Mr.  Knight  (page  39)  is  not  well 
founded.  We  are  not  positive  as  to  the  exact  date  of  intro- 
duction, but  we  present  in  Fig.  95  what  was  doubtless  the 
pioneer  instrument  of  the  top-auxiliary  type,  and  as  far  as  we 
have  been  able  to  determine,  it  was  made  for  Mr.  Wm.  Petherick, 
Superintendent  of  the  Copper  Falls  Mines,  Mich.,  1855-60, 
apparently  from  drawings  furnished  by  him. 

As  first  made,  the  auxiliary  telescope  was  clamped  on  the 
main  telescope,  about  the  same  as  compass-sights,  but  would 
never  clamp  in  line  with  the  main  telescope.  Then  the  uprights 


Petherick' s  Mine  Transit  with  the  First 
of  Top- Auxiliary  Telescopes. 


Page  45. 


t  Page  75. 


J  Page  39. 


158        THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS. 

were  attached  permanently  to  the  transit-telescope,  and  the 
auxiliary  only  was  made  detachable,  as  well  as  reversible,  "  end 
for  end  "  (somewhat  as  shown  in  Fig.  94) ;  but  in  this  form  the 
uprights  would  get  bent  in  the  mines,  and  render  the  attach- 
ment useless.  A  hinged  upright  was  then  tried,  similar  to  the 
folding  compass-sight  (Fig.  34,  above  cited),  but  the  hinge-pin 
would  wear,  and  the  uprights  rattle. 

The  writer's   plan,  introduced   in   1891,  is   to    mount    the 

FIG.  96. 


McNair's  Original  Inclined-Standard  Mine  Transit. 

uprights  upon  a  base-plate,  and  attach  it  to  the  main  telescope 
by  "  Y  "  bearings. 

When  Mr.  Scott  assumes*  that  the  inclined-standard  mining- 
transit  came  down  through  Seibert's  solar,  he  is  not  entirely 
correct.  As  a  matter  of  fact,  the  first  inclined  standards  made 
by  this  house  were  made  in  July,  1854,  for  Alexander  Roberts, 
of  Hamburg,  Pa.  In  the  next  year  we  made  one  of  the  same 
kind  with  long  center,  double  verniers  and  telescope-level,  but 

*  Page  47. 


THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS.          159 


FIG.  97. 


no  vertical  arc,  for  the  Philadelphia,  Wilmington  and  Balti- 
more E.E.,  but  we  have  no  photograph  or  further  description 
of  these  instruments.  From  this  time  on,  no  others  of  this 
pattern  seem  to  have  been  made  by  us  until  that  made  in  1875 
for  Thomas  S.  McE"air,  then  mining  engineer  for  the  Lehigh 
Valley  Coal  Company  at  Hazleton,  Pa.  It  was  at  this  time 
that  our  Mr.  Thomas  IS.  Watson,  in  the  course  of  the  argu- 
ment, suggested  the  principle  of  the  "  hinged  standards  "  by 
revolving  a  draughtsman's  triangle  on  one  of  its  corners.  The 
idea  was  rejected ;  but  it  seems 
to  us  now  that  if  unusually 
large  journals  had  been  used 
and  the  adjustment  had  been 
secured  as  in  the  horizontal 
axis  of  the  telescope,  it  could 
have  been  made  to  project  cor- 
rect alignments. 

Mr.  McNair's  instrument  is 
still  in  use,  and  is  reproduced 
here  (Fig.  96)  from  a  photo- 
graph kindly  prepared  by  that 
gentleman  especially  for  this 
discussion.  The  credit  for  first 
having  used  this  type  in  min- 
ing work  is  possibly  due  to 
Mr.  McNair ;  but  he  modestly 
refuses  to  accept  it  without  re- 
serve, observing,  "  The  an- 
cients, you  know,  are  said  to 
have  infringed  on  our  inven- 
tions." Attached  to  this  in- 
strument will  be  noticed  the  style  of  gradienter  introduced  by 
this  house  in  1872,  the  first,  we  believe,  to  appear  in  America. 
It  is  shown  more  in  detail  in  Fig.  97.  We  use  it  still,  for  the 
reason  that  it  is  not  so  exposed  as  the  other  style,  and  is 
equally  easy  to  read  and  manipulate. 

Of  distinctively  mining  transits,  there  are  probably  more  of 
the  inclined  standard  type  in  use  than  any  other,  all  objections 
to  its  eccentricity  and  "  overhang  "  melting  away  wherever  it 
has  once  been  used.  It  has  achieved  this  recognition  without 
any  special  recommendation  on  the  part  of  the  makers. 


Young's  Gradienter. 


160        THE    EVOLUTION    OF    MINE-SURVEYING    INSTRUMENTS. 

From  this  time  on,  the  desirability  of  combining  the  advan- 
tages of  MoN"air's  model  with  those  of  the  concentric  type  began 
to  occupy  the  minds  of  engineers.  In  1882,  Mr.  Peter  Brady, 
then  connected  with  the  Grlendon  Iron  Co.,  Easton,  Pa.,  sug- 
gested to  the  writer  the  advisability  of  designing  a  mining  in- 
strument (Fig.  98),  substantially  what  is  known  to-day  as  the 
duplex-bearing  mine-transit.  It  was  pointed  out  to  him  that 
the  structure,  with  all  the  necessary  appliances,  would  be  so 
cumbersome  as  to  merit  the  present  well-deserved  name  of 
"steam-engine;"  that  there 
would  be  great  difficulty  in 
keeping  the  bearings  free 
from  grit  and  in  proper  ad- 
justment, and  great  liability 
of  the  changeable  parts  to  in- 
jury ;  so,  upon  due  considera- 
tion, the  idea  was  abandoned. 

In  1854,  Edwin  J.  Hulbert 
ordered  of  us,  as  he  has  ex- 
plained, an  instrument  (Fig. 
9 9*) known  then  as  the  "Lake 


FIG.  99. 


Brady's  Proposition. 


Hulbert' s  First  Instrument. 


Superior  pattern."  Figs.  99  and  100  show  some  features  not 
clearly  seen  in  the  illustrations  given  by  Mr.  Hulbert.  In  Fig. 
99  the  upper  plate  was  semicircular,  8  inches  in  diameter,  read- 
ing by  a  single  vernier  to  minutes.  The  vernier  was  in  the 
clamping-arm  or  alidade  of  the  upper  limb,  and  was  also  provided 
with  a  small  tangent-screw.  The  telescope  was  provided  with  a 
vertical  arc,  clamp  and  tangent-screw  and  loose  vernier-arm,  as 


Compare  Fig.  90,  Page  148. 


THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS. 


161 


FIG.  100. 


introduced  by  Alfred  Young  in  1850.  The  side-telescope,  having 
a  level  attached,  was  mounted  on  a  free  vertical  circle,  6  J  inches 
in  diameter,  reading  by  two  verniers  to  minutes ;  a  clamp  and 
tangent  were  also  provided ;  all  mounted  on  a  compound  ball- 
and-socket  with  leveling  screws.  Not  many  of  these  instru- 
ments were  made.  While  seeming  to  fulfill  particular  re- 
quirements in  the  copper  regions  of  Michigan,  they  were  not 
favorites  with  the  instrument-maker,  on  account  of  the  peculiar 
shape  of  the  plates,  the  con- 
traction and  expansion  of 
which  were  apt  to  destroy 
the  adjustments;  and  the 
absence  of  the  needle  was 
at  that  time  a  popular  objec- 
tion on  the  part  of  the  engi- 
neer. 

Fig.  100  shows  what  was 
probably  the  first  side-aux- 
iliary telescope  attached  to 
a  mine- transit  in  America 
or  elsewhere.  It  was  made 
for  Mr.  Hulbert,  from  de- 
signs furnished  by  him,  as 
he  explains,  in  1856.  A  full 
vertical  circle  was  connected 
permanently  with  the  axle  of 

the  ^  transit-telescope.      The  Hulbert>8  Original  Side.Telescope  Transit<* 
auxiliary    telescope,    which 

alone  was  detachable,  was  attached  to  the  vertical  circle  by 
means  of  two  milled-head  clamp-screws. 

Fig.  101  illustrates  an  improvement  in  Mr.  Hulbert's  pat- 
tern. The  telescope  is  much  shorter  and  larger  in  diameter, 
and  is  permanently  connected  with  the  full  vertical  circle, 
which  is  also  made  detachable. 

Later,  several  methods  were  adopted  to  simplify  the  attach- 
ment of  a  side-auxiliary,  one  of  which  was  a  perforation  of  the 
horizontal  axis  large  enough  to  permit  the  insertion  of  a  spindle 
attached  to  the  telescope  (as  shown  in  Fig.  28 f).  The  objec- 


*  The  same  instrument  as  the  one  of  Fig.  91,  page  150. 


f  Page  34. 


162        THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS. 

tion  to  this  was  that,  unless  the  horizontal  axis  was  made  very 
heavy,  it  was  weakened  at  a  vital  point. 

Another  method  was  to  terminate  the  horizontal  axis  in  an 
enlarged  threaded  hub  beyond  the  outside  of  the  standard  and 
to  screw  the  telescope  on  with  a  clamping-nut,  as  in  Fig.  38,* 
but  as  the  threads  wore,  the  alignment  of  the  telescope  was  de- 
stroyed; and  while  the  parallelism  of  the  two  telescopes  was 
not  disturbed  to  any  marked  degree,  the  zero  (level)  points 
were,  and  it  was  necessary  for  the  engineer  to  allow  for  this 
index-error,  or  insert  a  piece  of  tin  foil  between  the  hub  at- 

FIG.  101. 


Improvement  on  Hulbert's  Mine-Transit. 

tached  to  the  telescope  and  the  side  of  the  standards.  Of  late 
years  it  has  been  customary  to  add  a  tangent-screw  or  two  op- 
posing screws  to  remedy  this  objection. 

Fig.  102,  illustrating  the  style  in  use  at  present  (1899),  is 
taken  from  a  transit  made  for  use  in  the  Kimberley  mines,  South 
Africa.  The  auxiliary  telescope  is  attached  permanently  to 
the  vertical  circle  (5  in.  in  diameter,  and  reading  by  a  single 
vernier  to  one  minute),  and  is  provided  with  a  clamp  and  a 
tangent-screw.  The  graduations  are  on  the  inside  of  the 
circle,  to  protect  them  from  injury,  and  to  facilitate  the  reading 
of  the  vernier.  The  telescope  (non-extension,  dust-  and  water- 

*  Page  42. 


THE    EVOLUTION    OF    MINE-SURVEYING    INSTRUMENTS.         163 

proof),  7  in.  long,  is  furnished  with  a  diagonal  (prism)  eye- 
piece and  a  reflector  for  cross-hairs  (the  latter  not  shown  in  the 


FIG.  102. 


Young  &  Sons'  Modern  Mine-Transit. 

figure).  All  the  attachments,  with  the  counterpoise,  are  de- 
tachable, and  when  they  are  not  in  use  the  engineer  has  still  a 
complete  transit,  with  all  modern  improvements,  having  a  gradu- 

12 


164        THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS. 

ated  plate  6|  in.  in  diameter,  level  to  telescope,  clamp   and 
opposing  screws  (not  shown  in  the  figure)  and  vertical  arc. 

FRANK  OWEN,  London,  Eng.  (communication  to  the  Secre- 
tary) :  The  following  detailed  description  of  the  "  Henderson 
Rapid  Traverser,"  alluded  to  by  Mr.  Scott*  and  by  Mr.  Brough,f 
may  be  of  interest.  I  am  indebted  for  it  to  the  courtesy  ot 
the  inventor,  my  former  teacher,  Mr.  James  Henderson,  M. 
Inst.  C.  E.,  of  Truro,  Cornwall,  England.  He  previously  in- 

FIG.  103. 


Henderson's  Kapid  Traverser. 

vented  the  Henderson  dial,J  a  circumferentor  with  four  sights, 
described  by  Brough  in  his  Mine  Surveying,  and  by  Stanley  in 
his  Surveying  Instruments.  The  present  account  is  based  on  a 
paper  read  by  Mr.  Henderson  before  the  Mining  Association 
and  Institute  of  Cornwall  in  December,  1893.  The  illustra- 
tions, Figs.  103  and  104,  are  taken  from  the  catalogue  of 
Messrs.  E.  T.  Newton  &  Son,  Camborne,  Cornwall,  the  makers 
of  the  Traverser. 

The  Kapid  Traverser  is  a  circular  brass  table  of  about  10  in.  in  diameter, 
mounted  on  a  tripod -stand  with  the  usual  leveling-screws,  and  having  a  brass 
alidade  or  ruler  that  revolves  around  a  fixed  center-pin,  and  that  has  at  each  end 
a  vertical  sight,  capable  of  being  replaced  by  an  arc  or  quadrant  when  angles  of 
considerable  elevation  or  depression  are  to  be  measured.  On  the  top  of  the 
table,  a  disk  of  enameled  zinc  is  securely  fixed  by  small  screws  and  nuts  and  by 
a  central  holding-down  brass  plate,  over  which  the  alidade  freely  passes. 
Bain  or  dropping  water,  or  even  washing  with  soap  and  water,  will  not  obliterate 
the  pencil-marks ;  yet  hard  scrubbing  will  remove  them,  and  the  disk  can  be 
used  repeatedly. 


*  Page  13. 


f  Page  69. 


t  Page  17. 


THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS. 


165 


The  surface  of  the  disk  has  five  concentric  rings  scratched  or  marked  upon  it 
by  means  of  a  pencil  inserted  in  five  small  notches  in  the  thick  edge  of  the 
alidade,  and  held  fast  while  the  disk  is  revolved.  The  fiducial  or  feather  edge  of 
the  alidade  has  corresponding  marks,  numbered  and  with  a  rectangular  notch 
opposite  each  division,  to  allow  the  letter  or  number  of  each  course  or  station  to 
be  marked  on  the  disk.  The  concentric  rings  are  to  prevent  the  overcrowding  of 
traverse  lines  in  any  one  direction,  and  enable  separate  surveys  to  be  made  with 
the  same  disk  without  interference.  The  table  carrying  the  disk  can  be  firmly 
clamped  to  the  tripod  head,  and  the  alidade  to  the  table  when  required.  The 
clamping  screws  for  each  are  distinguished  by  a  difference  in  form. 

FIG.  104. 


Disk  of  the  Rapid  Traverser  in  Use. 

In  use,  the  fiducial  edge  should  always  be  on  the  observer's  right  hand.  After 
clamping  the  table  and  sighting  the  alidade,  the  direction  is  marked  with  a  fine 
pencil-line  drawn  across  the  space  between  any  two  adjacent  concentric  rings. 
The  leading  direction  is  indicated  by  a  single  barb,  or  half  arrow,  at  one  end  of 
the  line ;  and  the  number  or  letter  of  the  course  is  written  within  the  notch  cut 
in  the  edge  of  the  alidade.  For  hilly  ground,  the  sight  at  each  end  of  the 
alidade  is  marked  in  degrees  up  to  25,  and  has  a  sliding-bar  so  fitted  that  by 
looking  through  the  eyehole  at  the  top  of  one  sight  and  setting  the  sliding-bar 
on  the  forward  object,  the  angle  of  inclination  can  be  read  and  noted.  Or,  for 
greater  accuracy,  the  quadrant  can  be  substituted  for  the  sights,  and  the  angles 
read  to  minutes.  The  telescope  attached  to  the  quadrant  revolves  on  a  vertical 
axis,  so  that  by  revolving  180°  to  a  mark  made  for  the  purpose,  back  sights  can 


166        THE    EVOLUTION    OF    MINE-SURVEYING    INSTRUMENTS. 

be  observed  without  shifting  the  alidade.  In  going  from  one  station  to  the  next, 
the  Traverser  is  removed  from  its  stand,  and  fixed,  with  the  alidade  still  clamped, 
on  the  forward  stand,  and  sighted  back  to  the  former  tripod  and  clamped.  Then 
the  alidade  is  undamped  and  a  sight  taken  to  the  next  station,  or  to  any  sub- 
sidiary station.  It  is  recommended  that  three  tripods  be  used  in  a  traverse  either 
underground  or  on  the  surface.  The  magnetic  meridian  can  be  taken  at  any 
convenient  station  by  means  of  a  trough-compass  placed  temporarily  against  the 
back  of  the  alidade.  The  distances  from  station  to  station  are  measured  sepa- 
rately, and  are  entered,  as  usual,  in  a  note-book. 

For  plotting,  the  disk  is  removed  from  the  brass  table,  and  placed  in  proper 
position  upon  the  intended  map,  with  one  or  more  meridian  lines  upon  it, 
and  is  held  firm  by  a  weight  or  two.  Then,  with  a  parallel  ruler,  best  a  rolling 
one,  the  successive  courses  of  the  survey  are  transferred  to  the  map.  The  disk 
becomes  a  protractor  of  great  accuracy,  and  the  plotting  is  more  rapid  than 
usual.  The  disk  may  be  kept  for  future  reference,  or  can  be  cleaned  off  by  scrub- 
bing with  soap  and  water,  or  with  india-rubber.  If  desired,  the  bearings  can  be 
read  off  rapidly,  by  means  of  an  alidade  moving  about  a  pin  in  the  centre  of  a 
protractor  over  which  the  disk  has  been  placed. 

The  Traverser  can  be  used  either  in  mines  or  on  the  surface ;  and  for  setting 
out  railway  or  other  road  lines  by  chords  of  any  length  previously  drawn  on  the 
disk,  with  the  lengths  thereof  noted  in  the  field-book. 

Clearly,  the  Traverser  is  based  on  the  plane-table  method,  and  is  really  a 
goniograph  or  angle-drawer  without  any  reading  or  booking  of  angles ;  but, 
unlike  the  plane-table,  it  is  not  used  for  plotting  the  survey  in  the  field.  The 
advantages  claimed  over  other  surveying  instruments  are  :  1.  A  great  saving  of 
time.  2.  Simplicity  of  construction,  and  consequently  comparative  cheapness. 
3.  Portability,  and  without  liability  to  damage.  4.  Great  simplicity  in  the  sub- 
sequent plottings. 

R.  "W.  RAYMOND,  New  York  City :  A  few  additional  notes 
may  help  towards  the  more  complete  elucidation  of  Mr.  Scott's 
main  subject. 

Astrolabe. — Reinhold*  explains  that  the  surveyor's  astrolabe 
(in  German  and  late  Latin,  astrolabiwri),  the  lower  part  of  Fig. 
105  (see  also  Fig.  83f),  is  properly  a  whole  or  a  half-circle  of 
brass,  graduated,  the  whole  circle  to  360°,  the  half  one  to 
180°,  with  a  pair  of  fixed  sights  at  the  ends  of  the  diameter, 
and  with  an  alidade  revolving  about  the  center  and  bearing  at 
the  ends  another  pair  of  sights.  The  Encyclopaedia  Britannica 
(under  Navigation)  gives  the  simpler,  older  form  of  the  astro- 
nomical astrolabe,  as  described  by  Martin  Cortes  in  his  book, 
The  Art  of  Navigation,  Seville,  1556,  and  copied  in  the  upper 
part  of  Fig.  105.  It  is  a  polished  circular  plate  of  copper  or 
tin,  6  or  7  inches  in  diameter,  purposely  weighty,  so  as  to  hang 

*  Geometric,  Forensis  oder  die  aufs  Reeht  angewandte  Messkunst,  C.  L.  Keinhold, 
Muenster,  1781,  1st  pt.,  p.  106.  t  Page  122. 


THE    EVOLUTION    OF    MINE-SURVEYING  INSTRUMENTS. 


167 


FIG.  105. 


steady  and  plumb  by  a  hole  at  the  top ;  and  graduated  to  de- 
grees in  the  upper  left-hand  quadrant,  and  some  years  later  in 
both  upper  quadrants;  and  there  is  a  pointer  of  the  same 
metal,  with  two  sights  upon  the  "  line  of  confidence,"  that 
passes  through  the  center. 

Eeinhold  further  says  that  the  astrolabe  has  later  been  en- 
riched and  improved  with  accessory  appliances,  as  he  illustrates 
by  Fig.  106,  showing  one  that  he  has  found  the  most  perfect. 
AB  is  the  whole  circle  divided  into  360° ;  CD,  the  alidade, 
with  a  vernier  at  each  end  indicating  5,  20,  30  or  60  minutes ; 
EF,  sights  high  enough  to  see  over  the 
iixed  sights  GH.  The  telescope,  JN",  re- 
volves about  0  vertically,  with  a  spirit- 
level  on  top,  and  with  the  half-circle, 
MLK,  joined  below  and  read  with  the 
index  L.  The  compass  P  rests  on  the 
alidade.  The  telescope  QE,  as  well  as 
JJST,  takes  the  place  of  the  sights  in  the 
case  of  distant  objects.  It  is  plain  that 
the  instrument  is  essentially  a  theodolite, 
much  resembling  the  instruments  of 
Figs.  16  and  17,*  except  that  the  tele- 
scope is  supported  by  a  single  central 
standard  instead  of  two  side  ones,  and 
the  verniers  are  upon  arms,  or  an  alidade, 
instead  of  a  plate. 

Evidently,  then,  the  word  astrolabe 
had,  in  surveying,  a  very  wide  range  of 
application,  from  the  simplest  semicircle  with  an  alidade  and 
two  pairs  of  sights  up  to  a  theodolite  with  two  telescopes,  with 
verniers,  or  even  with  a  compass. 

Zollmanri's  Disk. — Eeinhold  saysf  that  Zollmann's  disk,  Fig. 
107,  is  a  round  wooden  board  with  a  frame  to  enable  paper  to 
be  stretched.  There  is  an  alidade,  movable  horizontally  about 
a  pin  in  the  middle  of  the  disk.  The  instrument  is  nearly 
allied  to  the  plane-table,  but  resembles  yet  more  closely  Doug- 
las's Infallible,  of  1727,{  and,  like  that,  might  be  called  in  some 
sort  a  progenitor  of  Henderson's  Eapid  Traverser. 


C 


The  Astrolabe,  Simplest 
Forms  :  the  Upper,  As- 
tronomical ;  the  Lower, 
for  Surveying. 


Pages  18,  20. 


f  Op.  tit.,  p.  137. 


Page  69. 


168         THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS. 

FIG.  106. 


Reinhold's  Best  Astrolabe. 
FIG.  107. 


Zollmann's  Disk. 

Iron-Disk  (Eisenscheibe). — Yon  Hanstadt*  explains  that  the 
iron-disk  (Eisenscheibe)^  is  so  called,  not  on  account  of  its  ma- 

*  Avdeitung  zur  Markscheidekunst,  J.  N.  L.  von  Hanstadt,  Pesth,  1835,  p.  201. 
f  Mentioned,  and  illustrated  in  one  form,  by  Scott,  page  11. 


THE    EVOLUTION    OF    MINE-SURVEYING    INSTRUMENTS.          169 

terial,  but  because  of  its  use  in  iron-mines.  He  says  it  con- 
sists of  a  rather  large  brass  disk,  graduated  to  degrees  merely, 
and  from  left  to  right,  like  a  plane-table  compass.  It  turns  at 
the  middle  about  a  ball-and-socket  joint,  both  horizontally  and 
in  any  vertical  plane.  There  are  two  revolving  arms,  each  with 
a  hook  at  the  end,  to  which  are  attached  the  measuring  cords 
stretched  to  the  fore  and  back  stations.  There  are  three  hol- 
low brass  cylinders,  one  for  each  of  these  stations  and  one  for 
the  instrument-station,  with  iron  screw-points  below,  to  screw 
upon  a  plank  or  timber  set  across  a  mine-gangway*  or  upon  a 
wooden  plug.  The  three  cylinders  are  of  exactly  equal  height 
and  large  enough  inside  to  receive  the  ball-and-socket  joint 
under  the  disk.  But  when  the  instrument  with  this  joint  is  set 
in  the  middle  cylinder,  the  fore  and  back  cylinders  are  filled 
each  with  a  wooden  plug  having  a  projecting  hook,  to  which 
the  measuring  cords  are  attached.  Von  Hanstadt  says  the  ap- 
paratus is  pretty  clearly  illustrated  and  described  in  Moehling's 
Markscheidebuch  of  1793 ;  but  is  not  to  be  recommended  for 
accurate  surveys  :  1.  Because  you  do  not  dare  to  stretch  the 
cord  tight  enough,  since  the  screw-points  of  the  cylinders  easily 
break  or  bend.  2.  At  stations  where  the  courses  make  a  sharp 
angle,  the  ball-and-socket  joint  is  under  a  strong  pressure,  that 
makes  the  turning  of  the  disk  difficult,  and  causes  pretty 
strong  friction  upon  the  two  brass  arms,  so  that  you  cannot  be 
sure  the  correct  angle  is  indicated.  3.  It  is  often  difficult  to 
set  the  instrument  again  precisely  over  a  station  for  subsequent 
work,  since  the  cross-plank  cannot  always  be  left  in  place.  4. 
The  reckoning  up  of  the  courses  of  an  extensive  survey  takes 
too  much  time  and  patience. 

Von  Hanstadt' s  Mine- Theodolite. — Von  Hanstadt  says  he  con- 
sequently devised  another  instrument  that  may  fitly  be  called  a 
mining-theodolite.  This  is,  perhaps,  sufficiently  illustrated  in 
Fig.  108,  compiled  from  his  fragmentary  drawings.  The  ali- 
dade with  the  sights  is  about  2  feet  long.  The  brass  plate  ^, 
before  the  instrument  proper  is  set  upon  it,  is  first  leveled  with 
a  movable  spirit-level,  II,  and  bears  the  fixed  spindle  v,  about 
which  the  upper  part  of  the  instrument  revolves.  This  the- 
odolite, rightly  so  called,  has  the  telescope  replaced  by  sights, 

*  See  page  38,  Fig.  33. 


170        THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS. 

FIG.  108. 


Von  Hanstadt's  Mine-Theodolite,  Nearly  |  Full  Size. 


with  virtually  a  single  central  support  for  them  ;  but  has  the 
semicircle  attached  below  them,  in  the  way  peculiar  to  theodo- 
lites. 

Combes'  's    Mine-  Theodolite.  —  The    mine-theodolite    of   Prof. 


THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS.          171 
FIG.  109. 


Combes' s  Mine-Theodolite,  Plan. 
FIG.  110. 


Combes' s  Mine-Theodolite,  Side  View. 

Combes,  of  the  Paris  Ecole  des  Mines,  was  described  by  him  in 
1836,*  in  an  article  giving  full  details  of  its  construction  and 

*  Memoire  sur  les  leves  de  plans  souterrains  et  description  d'un  nouvel  instrument, 
propre  a  remplacer  la  boussole  et  le  demi-cercle  suspendus ;  par  M.  Combes,  professeur 
d*  exploitation  d  I*  Ecole  royale  des  mines.  (Annales  des  Mines,  3d  series,  vol.  ix.,  1836, 
pp.  81  and  217.) 


172  HISTORY    OF    SOLAR    SURVEYING   INSTRUMENTS. 

examples  of  its  use.  Figs.  109  and  110  will  sufficiently  explain 
it  for  the  purpose  of  this  notice.  Fig.  109  is  a  plan  of  the  in- 
strument, as  seen  from  above,  and  Fig.  110  a  lateral  view  of 
the  telescope  and  vertical  circle. 

Combes  calls  the  instrument  a  mine-theodolite ;  and  it  is  a 
theodolite  in  a  common,  wide  sense  of  the  word.  But  the  tel- 
escope has  the  characteristic  that  distinguishes  the  transit  from 
the  theodolite ;  namely,  the  capacity  of  completely  revolving  in 
a  vertical  plane.  The  telescope,  however,  is  supported  on  only 
one  side,  just  as  it  is  in  the  astronomical  mural  circle,  first  de- 
vised by  Maskelyne  and  used  at  the  Greenwich  Observatory  in 
1811 ;  and  just  as  it  had  been  in  the  lunette  murale,  and  again  in 
the  yet  older  mural  quadrant,  first  described  (of  course,  with 
sights  instead  of  the  telescope)  by  Ptolemy*  about  A.D.  150,  and 
constructed,  avowedly  on  his  model,  by  N~asir-eddin  in  Persia 
in  1260,  but  formerly  supposed  to  have  been  invented  by  Tycho 
Brahe  about  1581.  Since  the  telescope  supported  on  only  one 
side  tends  by  its  weight  and  wear  to  sag  downward,  so  as  not 
to  revolve  in  a  truly  vertical  plane,  it  is  now  discountenanced, 
especially  for  observing,  not  a  vertical  angle,  but  the  transit  of 
a  star  across  the  meridian ;  and  preference  is  given  to  the  astro- 
nomical transit-telescope,  which  is  supported  on  both  sides,  and 
has,  moreover,  an  axle  capable  of  reversion,  end  for  end, — the 
invention  of  Roemer  in  1700. 


History  of  Solar  Surveying  Instruments. 

BY  J.   B.   DAVIS,   CLEVELAND,    OHIO. 
(Canadian  Meeting,  August,  1900.) 

THIS  paper  has  been  prepared  at  the  suggestion  of  Mr.  Dun- 
bar  D.  Scott,  to  supplement  his  "  Evolution  of  Mine-Surveying 
Instruments." 

Before  entering  into  a  detailed  history  of  solar  instruments, 
a  few  remarks  will  be  made  touching  upon  land-surveys  in 
general,  and  on  what  has  led  to  the  development  of  these  in- 
struments. 

*  Tycho  Brake,  by  J.  L.  E.  Dreyer,  Ph.D.,  Director  of  the  Armagh  Observa- 
tory ;  Edinburgh,  1890  ;  p.  320. 


HISTORY  OF  SOLAR  SURVEYING  INSTRUMENTS.  173 

IMPORTANCE  OF  SOLAR  SURVEYING. 

The  True  Meridian  Needful. — First  of  all,  there  is  strong  rea- 
son for  the  opinion  that  all  land-surveys  should  be  referred  to 
the  true  meridian. 

Description  by  courses  and  distances  is  found  in  most  deeds 
conveying  real  estate,  and  in  records  perpetuating  the  results 
of  surveys.  There  are  two  noteworthy  exceptions :  namely,  in 
cities  and  villages,  conveyances  of  land  are  often  made  by  lot- 
numbers  ;  and  the  United  States  government  describes  the  land 
granted  by  its  patents  by  reference  to  its  general  rectangular 
system  of  public  land-surveys,  without  special  rehearsal  of  the 
courses  and  distances  bounding  each  grant.  Outside  of  these 
exceptions,  the  description  by  courses  and  distances  is  perhaps 
the  most  simple  and  comprehensive  method  available ;  at  all 
events,  long  custom  has  decreed  its  employment. 

Survey-lines  are  usually  marked  or  monumented ;  but  the 
marks  are  not  always  suitably  clear  and  prominent,  and  duly 
recorded  in  the  conveyance.  Moreover,  they  may  be  lost  or 
destroyed  through  carelessness  and  ignorance  of  their  value; 
and,  sooner  or  later,  the  lines  must  be  retraced  by  a  new  sur- 
vey— with  what  difficulty,  when  the  original  courses  were  taken 
by  needle,  only  the  surveyor  knows.  All  that  he  can  do  is  to 
turn  for  help  to  the  facts  of  possession,  or  to  adjacent  surveys ; 
or,  if  an  original  corner  can  be  found  as  a  starting-point,  to 
satisfy  himself,  as  to  courses,  with  the  limit  of  error  in  a  needle- 
instrument,  while,  as  to  distances,  he  must  determine,  as  nearly 
as  may  be,  the  difference  in  length  between  his  steel  tape  and 
the  worn  and  kinky  Gunter's  chain  of  the  former  survey. 
These  perplexing  problems  we  must  continue  to  encounter 
until  more  accurate  modern  surveys  shall  have  replaced  the 
original  ones. 

The  remarks  apply  also  to  the  rectangular  system  of  survey- 
ing United  States  lands,  so  far  as  the  relocation  of  sub-divi- 
sional lines  may  be  affected  by  the  uncertainty  of  'the  indica- 
tions of  the  magnetic  needle. 

But  I  wish  to  call  particular  attention  to  what  may  be  termed 
an  inconsistency  in  our  modern  land-surveys.  Increased  ac- 
curacy in  them  is  demanded  by  the  increase  of  land-values. 
Hence,  measurements  are  more  accurately  made ;  a  transit  is 
used ;  and  more  care  is  taken  in  monumenting ;  so  that  the  sur- 


174  HISTORY    OF    SOLAR    SURVEYING   INSTRUMENTS. 

veys  may  be  retraced  with  little  difficulty,  provided  monuments 
enough  are  left  for  starting-points.  At  the  same  time,  custom 
having  prescribed  the  method  of  description,  we  still  use  courses, 
determined  not  by  the  needle,  as  originally,  but  by  deducing  the 
bearings  from  the  transit-angles  taken ;  and  we  use  as  a  base  the 
bearing  of  some  one  line,  either  measured  in  the  field  or  copied 
from  a  deed.  Eight  here  comes  in  the  inconsistency :  we  care 
nothing  whether  the  bearing  of  the  line  we  start  from  be  a  true 
one  or  not.  We  are  well  satisfied  if  it  be  only  approximately 
true ;  we  rely  on  the  harmony  of  our  survey,  the  fact  that  we 
have  set  monuments,  have  taken  the  angles  with  a  transit,  and 
have  made  our  measurements  carefully ;  and  we  assume  that 
there  can  be  no  future  difficulty  in  retracing  the  survey  we  have 
made.  But  the  bearings  of  the  lines  in  this  modern  and  ac- 
curate survey,  taken  individually,  mean  absolutely  nothing  so 
far  as  the  retracing  of  an  accurate  survey  is  concerned ;  only 
collectively  are  they  of  any  value. 

If  we  are  to  make  an  accurate  survey,  and  are  by  custom 
forced  to  the  use  of  bearings  in  our  descriptions,  why  not  have 
the  bearings  mean  something,  and  be  consistent  with  the  rest  of 
the  survey  ?  But  that  is  not  all :  monuments  are  lost,  and  the 
cases  are  not  infrequent  when  only  one  can  be  found ;  and  then 
trouble  begins,  and  care  and  good  judgment  are  required  in 
the  solution  of  the  problem.  Evidently,  the  remedy  is  to  refer 
the  survey  to  the  true  meridian.  This  can  be  done  by  observ- 
ing the  north  star,  or  an  altitude  of  the  sun,  or  by  a  solar  in- 
strument. Only  by  a  reference  to  the  true  meridian  can  the 
"  one  stone  problem  "  be  at  all  times  satisfactorily  solved. 

Old  Methods  of  Meridian  Determination. — The  earliest  instru- 
mental methods  of  determining  the  true  meridian  in  this  coun- 
try, as  well  as  in  Europe,  were,  first,  by  observing  the  polar 
star,  taking  into  account  its  travel  in  an  orbit  the  distance  of 
which  from  the  projected  axis  of  the  earth  is  known;  secondly, 
by  an  altitude-observation  of  the  sun  and  the  subsequent  cal- 
culation of  the  spherical  triangle  of  which  the  sun,  the  zenith 
and  the  pole  are  at  the  vertices. 

Surveyors  do  not  take  very  kindly  to  observing  the  north  star, 
and  will  resort  to  it  only  when  absolutely  necessary,  because 
they  object  to  the  requisite  night-work.  The  method  of  deter- 
mining the  azimuth  by  an  altitude  of  the  sun  does  not  seem  to 


HISTORY    OF    SOLAR    SURVEYING   INSTRUMENTS.  175 

be  popular,  since  it  requires  too  much  time  for  the  calculation 
of  the  spherical  triangle. 

Davis's  Solar  Screen. — It  is  appropriate  here  to  mention  the 
solar  screen  invented  by  Prof.  J.  B.  Davis,  of  the  University  of 
Michigan,  Ann  Arbor,  Mich.,  and  perfected  by  the  firm  of  Buff 
&  Berger,  Boston,  Mass.  It  has  been  illustrated  and  described 
by  Mr  Scott,*  Fig.  59.  The  invention  does  not  belong  in  the 
same  class  as  the  mechanical  solars  to  be  described  below ;  for 
it  is  not,  strictly  speaking,  a  solar  attachment,  but  rather  an  ap- 
pliance for  more  conveniently  sighting  the  sun  centrally  in  a 
direct  solar  observation.  The  use  of  the  solar  screen  does  not 
reduce  the  necessary  computation,  so  far  as  the  solving  of  the 
spherical  triangle  is  concerned  ;  for  this  work  must  still  be  done 
after  the  altitude  of  the  sun  is  observed. 

HISTORICAL  SKETCH  OF  SOLAR  SURVEYING-INSTRUMENTS. 

As  the  theory  and  practice  of  solar  work  are  now  fully 
treated  in  all  standard  text-books  on  surveying,  their  full  dis- 
cussion is  not  deemed  desirable  here,  and  in  what  follows,  a 
sufficient  knowledge  of  astronomy  in  its  application  to  solar 
work  is  presupposed. 

Government  Land-Surveys. — On  May  7,  1784,  the  committee 
appointed  by  the  Continental  Congress,  of  which  Thomas  Jef- 
ferson was  chairman,  recommended  that  all  public  lands  be 
divided  into  squares  ten  geographical  miles  on  a  side,  and  these 
sub-divided  into  lots  of  one  square  mile;  but  a  subsequent 
amendment,  made  April  26,  1785,  in  which  is  recorded  the 
first  mention  of  "  townships "  and  "  sections,"  required  that 
the  main  divisions  should  be  only  seven  miles  square,  marked 
by  lines  running  due  north  and  south,  and  others  crossing  at 
right-angles.  This  ordinance,  as  still  further  amended,  May 
20,  1785,  with  a  provision  for  townships  containing  thirty-six 
sections  each,  must  be  regarded  as  the  actual  beginning  of  our 
present  government  system  of  land-surveys ;  and  General  Eufus 
Putnam  must  be  looked  upon  as  its  founder. f 

Burt's  Solar  Compass. — In  1833  Wm.  A.  Burt,  of  Mt.  Yernon, 
Mich.,  received  an  appointment  as  U.  S.  Deputy  Surveyor,  and 

*  Page  65. 

|  See  the  article  by  Col.  H.  C.  Moore  in  the  Jour.  Ass'n  Engineering  Societies, 
vol.  ii.,  p.  282. 


176 


HISTORY    OF    SOLAR    SURVEYING    INSTRUMENTS. 


began  work  with  an  ordinary  compass-instrument,  as  prescribed 
by  the  government.  He  found  frequent  occasion  to  reprove  his 
chainmen,  believing  them  to  be  guilty  of  gross  inaccuracies.  It 
turned  out  that  the  chainmen  were  correct  enough  in  their  work, 
and  that  the  trouble  was  due  to  the  treacheries  of  the  magnetic 
needle.  Mr.  Burt  satisfied  himself  that  he  could  not  sufficiently 
rely  upon  the  accuracy  of  the  indications  of  the  needle ;  and 
he  must  also  have  concluded  that  the  methods  of  determin- 
ing the  meridian  by  sighting  Polaris  or  observing  the  sun's 
altitude  were  not  practicable  in  the  class  of  surveys  upon  which 

FIG.  111. 


Burt' s  Original  Solar  Attached  to  a  Compass. 

he  was  engaged.  At  all  events,  he  began  systematical  work  in 
developing  a  mechanical  solar.  By  1835  he  was  in  Philadel- 
phia, placing  the  model  of  his  device  in  the  hands  of  instru- 
ment-maker Wm.  J.  Young;  and  in  the  same  year  his  com- 
pleted instrument  received  the  Scott  medal  from  the  Franklin 
Institute.  That  instrument,  shown  in  Fig.  Ill,  was  designed 
to  solve  mechanically  the  celestial  triangle,  and  consisted  mainly 
of  three  arcs — the  latitude-arc,  the  declination-arc,  and  the  hour- 
circle. 

Burt's  solar  compass  did  not  attain  perfection  until  about 


HISTORY    OF    SOLAR    SURVEYING   INSTRUMENTS. 


177 


1850.  It  then  came  into  general  use,  and  was  for  many  years 
the  standard  instrument  used  in  surveys  of  the  United  States 
public  lands.  He  exhibited  the  perfected  instrument  (Fig.  112) 
at  the  London  Exhibition  of  1851 ;  and  Sir  John  Herschel 
then  said :  "  I  have  long  understood  the  elements  of  your  in- 
strument, but  could  not  see  how  they  would  be  carried  out 
mechanically.  It  has  fallen  to  your  lot,  Sir,  not  only  to  con- 
ceive the  necessary  astronomical  elements,  but  also  to  carry 
them  into  practical  effect  mechanically."  The  same  instrument 
was  a  part  of  the  government  exhibit  at  the  Columbian  Exposi- 
ion  in  Chicago,  and  has  now  been  added  to  the  instrumental 

FIG.  112. 


Burt's  Improved  Solar. 

collection  prepared  for  Paris.  It  is  probably  not  too  much  to 
say  that  with  Burt's  solar,  or  some  adaptation  of  it,  fully  80  per 
cent,  of  the  public  lands  of  the  United  States  have  been  laid 
out.  The  opinions  of  authorities  on  solar  work  in  connection 
with  government  surveys  would  indicate  that  Prof.  Baker's 
broad  statement,  quoted  by  Mr.  Scott,*  is  without  warrant  and 
misleading. 

Yeiser's  Meridian  Instrument. — In  1861  Frederic  Yeiser,  of 
Danville,  Ky.,  introduced  a  meridian-instrument,  Fig.  113,  the 
operation  of  which  was  founded  on  the  ancient  method  of 

*  Page  43. 


178 


HISTOKY    OF    SOLAR    SURVEYING   INSTRUMENTS. 


bisecting  the  arc  found  by  the  observation  of  equal  altitudes  of 
the  sun.  Two  parallel  disks  were  connected  by  a  vertical  pillar. 
On  the  face  of  the  upper  plate  revolved  a  sort  of  alidade  bev- 
eled along  one  edge  at  one  end,  and  carrying  at  the  other  end 
the  lens-bar  of  the  Burt  solar.  An  observation  was  made  at 
a  certain  hour  in  the  morning,  and  the  lens-bar  was  clamped  to 
the  vertical  quadrant.  In  the  afternoon,  at  a  corresponding 
hour,  the  upper  part  of  the  instrument  was  moved  about  on  the 

FIG.  113. 


Yeiser's  Meridian  Instrument. 

central  pivot  until  the  sun's  image  fell  at  the  intersection  of  the 
"  equatorial "  and  "  hour  "  lines.  Having  drawn  a  pencil-line 
along  the  beveled  edge  of  the  alidade  at  each  observation,  the 
line  that  bisected  the  intervening  space  or  arc  was  accepted  as 
the  meridian. 

Schmoltz's  Solar  Transit. — The  next  modification  of  the  Burt 
solar  has  been  referred  to  by  Mr.  Scott*  as  having  been  intro- 
duced in  1867,  when  the  transit  was  coming  into  more  general 

*  Page  43. 


HISTORY    OF    SOLAR    SURVEYING   INSTRUMENTS. 


179 


use,  by  Win.  Schmoltz,  an  instrument-maker  of  San  Francisco. 
Since  1874  it  has  been  mounted  by  Gurley,  as  in  Schmoltz's 
model,  upon  the  transverse  axis  of  the  transit-telescope,  but 
with  a  means  of  adjusting  the  polar  axis  to  movement  in  a 
truly  vertical  plane  (see  Fig.  38*).  It  is  essentially  the  Burt 
declination-arc  mounted  upon  its  polar  axis,  which  is  now  re- 

FIG.  114. 


Schmoltz-Gurley  Solar  Transit,  with  Jones's  Latitude-Arc. 

versed  from  its  position  in  Burt's  compass,  and  may  be  secured 
to  the  telescope,  or  removed,  by  means  of  the  thumb-screw  at 
the  top  of  the  polar  axis.  It  was  customary  to  lay  off'  the 
latitude  on  the  transit's  vertical  circle  or  arc ;  but  in  the 
Schmoltz-Gurley  model,  reproduced  in  Fig.  114,  the  patent 
latitude-arc  introduced  by  R.  M.  Jones  in  1883  is  used  instead. 

*  Page  42. 
13 


180 


HISTORY    OF    SOLAR    SURVEYING    INSTRUMENTS. 


This  arc  consists  of  an  inner  quadrant  reading  to  minutes,  and 
an  outer  segment  reading  to  ten  seconds  of  arc.  The  inner 
quadrant  carries  a  reversible  bubble-tube,  which  is  adjusted  for 
exact  horizontality  when  the  sun  is  in  the  meridian ;  and  in  all 
subsequent  settings  of  the  latitude  the  bubble  is  simply  brought 
back  to  the  center  of  its  scale.  This  design  of  Schmoltz  was 
one  of  the  first,  if  not  the  very  first,  of  the  successful  attempts 
to  combine  the  solar  attachment  with  the  ordinary  transit- 
instrument;  though  there  had  been  a  great  deal  of  experiment- 

FIG.  115. 


Lyman's  Solar  Transit. 

ing  to  improve  on  Burt's  last  model,  in  which  a  small  tele- 
scope was  mounted  upon  one  of  the  sights,  or  set  in  Y-bearings 
across  the  top  of  both  sights. 

Lyman's  Solar  Transit. — In  1869  Benjamin  S.  Lyman,  of 
Philadelphia,  devised  the  solar  apparatus  shown  in  Fig.  115. 
Wm.  J.  Young  &  Co.  (that  is,  Mr.  Young  and  his  partner, 
Charles  S.  Heller)  had  strongly  advised  him  against  placing  the 
solar  apparatus  on  the  top  of  the  telescope,  and  against  using 
inclined  standards  for  the  telescope.  The  apparatus  was,  there- 


HISTORY    OF    SOLAR    SURVEYING   INSTRUMENTS.  181 

fore,  placed  beneath  the  plates,  for  steadiness  and  protection 
against  exposure ;  and  was  so  designed  that  it  could  be  used 
with  a  plane-table  or  other  surveying  instrument.  The  usual 
six-inch  lens-bar  was  reduced  in  length  to  only  two  inches ;  but 
the  proper  focus  and  size  of  the  sun's  image  was  maintained 
by  the  total  reflection  of  two  rectangular  prisms.  Mr.  Lyman 
filed  a  caveat  of  his  invention  in  September,  1869,  had  the  same 
description  privately  printed  as  specifications  in  December, 
1870,*  secured  letters-patent  in  1871,  and  the  first  instrument 
was  made  in  1872. 

"It  is  true,"  says  Mr.  Lyman,  "that,  owing  to  the  greater  length  of  the  lens- 
bar  in  Burt's  compass,  the  latitude-arc  has  a  decidedly  longer  radius  and  the 
declination-arc  one  slightly  longer  ;  but  the  radius  of  both  arcs  in  the  solar  tran- 
sit is  two  inches  and  a  half,  or  the  same  as  for  the  vertical  and  horizontal  gradu- 
ations of  the  transit  proper,  the  size  that  is  usually  found  convenient  for  reading 
to  a  single  minute  with  a  vernier." 

When  the  vernier  of  the  latitude  arc  reads  90°,  the  polar 
axis  is  truly  vertical.  The  entire  attachment  weighs  about  a 
pound.  In  1877  Young  &  Sons  so  constructed  it  that  it  could 
be  attached  and  detached  at  pleasure. 

Seibert's  Solar  Transit. — About  1869  (but  it  is  not  now  possi- 
ble to  determine  the  exact  year)  F.  R.  Seibert,  then  with  the 
U.  S.  Coast  Survey,  had  Wm.  J.  Young  &  Co.  make  for  him 
a  transit  with  inclined  standards,  and  place  the  solar  apparatus 
directly  over  the  compass,  very  much  as  in  the  original  Burt 
instrument.  The  standards  were  inclined  forward,  so  as  not  to 
cast  a  shadow,  or  otherwise  interfere  with  the  successful  manip- 
ulation of  the  solar  apparatus.  It  was  to  this  instrument  (Fig. 
116)  that  Mr.  Scott  assigned!  the  probable  origin  of  the  in- 
clined-standard mine-transit ;  but  from  Mr.  A.  C.  Young's  con- 
tribution it  appears  that  inclined  standards  were  used  as  early 
as  1854  in  Mr.  Roberta's  instrument.^  Still,  it  is  possible  that 
the  inclined  standards  made  for  him  were  inclined  toward 
each  other,  forming  a  truss-support  for  the  telescope. 


*  Specifications  of  Improvements  in  Solar  Compasses.  B.  S.  Lyman.  Bengal  Print- 
ing Co.,  Calcutta,  1870.  The  specifications  and  caveat  mention  the  former  use  of 
inclined  standards,  undoubtedly  Seibert's  plan,  showing  that  it  dates  at  least  as 
far  back  as  1869. 

f  Page  47.  J  Page  158. 


182 


HISTORY    OF    SOLAR    SURVEYING   INSTRUMENTS. 


Pearsons's  Solar  Attachment. — On  July  27,  1875,  Harrison  C. 
Pearsons,  of  Ferry sburg,  Mich.,  patented  an  attachment  (Fig. 
117),  having  the  polar  axis  parallel  to  the  optical  axis  of  the 
telescope,  and  the  hour-circle  at  right  angles  to  it.  As  usual, 
the  declination-plate  revolved  upon  the  polar  axis;  but  the  lens- 
bar  was  provided  with  a  vernier  as  well  as  a  lens  and  equatorial 

FIG.  116. 


Seibert's  Solar  Transit. 

lines  at  each  end,  and  was  mounted  upon  gimbals  or  a  universal 
joint,  whereby  it  could  be  brought  at  will  to  the  surface  of 
either  broad  face  of  the  declination-plate.  Also,  the  declina- 
tion-plate was  graduated  on  both  its  broad  faces,  so  that  it  was 
possible  to  reverse  the  apparatus,  in  order  to  correct  errors  aris- 
ing from  unavoidable  imperfection  of  construction  and  adjust- 
ment. It  was  the  inventor's  idea,  as  expressed  in  his  letters- 


HISTORY    OF    SOLAR    SURVEYING   INSTRUMENTS. 


183 


patent,  to  utilize  the  telescope  itself  as  the  axis  of  the  hour-arc ; 
and  this,  to  the  best  of  my  knowledge,  is  the  first  suggestion 
of  letting  the  telescope  of  the  transit-instrument  become  the 
polar  axis.  The  manufacture  of  the  attachment  was  first  placed 
in  the  hands  of  the  Gurleys,  but  the  alliance  between  the  man- 
ufacturers and  the  inventor  was  not  a  successful  one. 


FIG.  117. 


Pearsons' s  Original  Attachment. 

Buff  $  Berger's  Pearsons  Solar  Attachment. — As  first  made 
by  Buff  &  Berger,  in  1878  (Fig.  118),  the  polar  axis,  while  still 
parallel  to  the  optical  axis  of  the  telescope,  was  placed  over  the 
bearings  at  one  side,  and  was  provided  with  a  spirit-level  on 
the  "clamping-arc,"  to  regulate  it  for  true  horizontality  before 
elevation  to  the  observer's  latitude.  This  was  especially  de- 
sirable, as  it  was  a  part  of  the  improvement  to  make  it  possible 
to  attach  or  detach  the  whole  apparatus  as  desired.  After  the 
latitude  was  set  off,  and  the  "  clamping-arc  "  carrying  the  solar 
was  clamped  to  the  standard,  the  telescope  was  free  to  move  in 
altitude  without  interfering  with  the  position  of  the  attach- 


184 


HISTORY    OF    SOLAR    SURVEYING   INSTRUMENTS. 


raent.  The  lens-bar  was  made  single,  instead  of  double,  with 
a  ground-glass  focal  plate,  so  that  the  sun's  image  could  be  ob- 
served from  the  rear  with  the  ordinary  reading-glass.  But  in 
1879  Mr.  Berger  began  substituting  for  it  a  small  telescope  of 
half-inch  aperture  and  six-inch  focus. 

FIG.  118. 


Buff  &  Berger' s  Pearsons  Solar. 

Buff$  Berger' s  Solar  Attachment. — In  1882  the  Pearsons  pat- 
ents were  assigned  to  Buff  &  Berger;  and  in  1885  the  general 
design  was  changed  so  that  the  declination,  as  well  as  the  lati- 
tude, could  be  laid  off  by  the  vertical  circle.  Fig.  119  shows  this 
last-mentioned  model.  The  attachment  is  fastened  by  a  screw 


HISTORY    OP    SOLAR    SURVEYING   INSTRUMENTS.  185 

to  an  extension  of  one  end  of  the  transverse  axis  of  the  tele- 
scope, and  to  the  other  end  is  clamped  the  latitude-level. 

Holmes' 's  Solar  Theodolite. — In  1878  J.  W.  Holmes,  instrument- 
maker  in  Batavia,  "N.  Y.,  placed  the  telescope  of  a  theodolite  so 
as  to  work  upon  the  declination-arc,  or  circle,  in  a  very  remark- 
able manner  (Fig.  120).  Between  the  standards,  in  the  usual 
position  of  a  telescope  in  an  ordinary  transit,  he  placed,  in  a 
plane  at  right  angles  to  the  vertical,  a  second  circle,  called  the 
"  dial-plate,"  graduated  to  read  minutes.  Within  this  ring  re- 

FIG.  119. 


Buff  &  Berger's  Solar  Attachment. 

volved,  upon  what  might  be  termed  the  polar  axis,  a  disk  that, 
together  with  the  "  dial-plate,"  was  also  journaled  at  right- 
angles  in  the  axis  of  the  vertical  arc.  The  disk  carried  the  tel- 
escope on  Y-bearings  centered  over  the  plates  below ;  and  upon 
the  disk  was  fastened  the  declination-arc  at  one  side  of  the  tel- 
escope. The  telescope  was  pivoted  to  the  declination-arc  by 
means  of  the  Y-bearing  nearest  the  ocular  and  could  be  moved 
in  altitude  at  the  objective  end  as  required,  and  regulated  to 
the  nearest  ten  seconds  of  arc.  Mr.  Holmes's  instructions  for 
the  use  of  the  instrument  are : 


186 


HISTORY    OF    SOLAR    SURVEYING    INSTRUMENTS. 


"Clamp  the  vertical  arc  to  the  latitude  of  the  place,  turning  the  dial-plate 
toward  the  north,  if  in  north  latitude.  Move  the  telescope  upon  the  declina- 
tion-arc to  the  angular  value  of  the  sun's  declination,  corrected  for  time  and 
refraction.  But  if  the  observation  is  made  in  south  latitude,  the  telescope  should 
be  reversed  in  its  Y's  so  that  the  object-glass  shall  be  at  the  pivot  of  the  declina- 
tion-arc. Turn  the  upper  part  of  the  instrument  upon  the  dial-plate,  and  the 
whole  instrument  upon  its  vertical  axis,  if  need  be,  until  the  telescope  can  be 
centered  upon  the  sun.  Now  the  upper,  or  equatorial  plates,  are  in  a  plane  par- 
allel to  that  of  the  equato*r ;  and  when  [ever]  the  telescope  is  [afterwards] 
brought  back  to  the  zero  of  the  graduations,  it  is  in  the  true  meridian." 

FIG.  120. 


Holmes' s  Solar  Theodolite. 

The  theodolite-type  of  the  instrument  made  it  necessary  to 
counterbalance  the  eccentricity  of  the  telescope  and  the  other 
superimposed  parts,  by  elongating  the  polar  axis  and  consider- 
ably increasing  its  weight. 

Smith's  Solar  Transit. — On  September  14, 1880,  Benjamin  H. 
Smith,  of  Denver,  Colo.,  made  the  telescopic  polar  axis  a  prac- 
tical invention.  To  do  this,  however,  he  employed  an  entirely 


HISTORY    OF    SOLAR    SURVEYING   INSTRUMENTS. 


187 


separate  telescope,  to  which  are  attached  declination-  and  lati- 
tude-arcs, as  shown  in  Fig.  121.  To  the  side  of  a  specially-de- 
signed standard  is  fixed  a  latitude-arc,  in  the  form  of  a  semi- 
circle, carrying  two  collars  or  bearings  on  its  diameter,  in  which 
the  solar  telescope  is  free  to  rotate  on  its  axis  to  any  required 
position,  as  indicated  by  the  hour-circle  which  circumscribes 
it.  At  the  object-end  of  the  telescope  is  a  prism  or  reflector, 

FIG.  121. 


Smith's  Solar  Transit. 

to  which  is  attached  an  arm,  at  whose  opposite  end  is  a  vernier 
that  reads  zero  on  the  declination-arc  when  the  plane  of  the  re- 
flector is  at  45°  to  the  optical  axis  of  the  telescope.  Hence,  if, 
after  the  proper  latitude  and  declination  are  set  oif,  the  telescope 
is  rotated  on  its  own  longitudinal  axis,  the  reflected  line  of  colli- 
mation  will  describe  a  celestial  equator;  and,  both  telescopes  being 
in  parallel  planes,  each  will  be  in  the  plane  of  the  meridian. 
Since  1895,  Mr.  Young  has  mounted  the  solar  telescope  in 


188 


HISTORY    OF    SOLAR    SURVEYING   INSTRUMENTS. 


Y-bearings  on  the  top  of  the  main  telescope,  as  shown  in  Fig. 
122 ;  and  so  has  dispensed  with  the  original  design  of  the  lati- 
tude-arc, in  favor  of  the  vertical  circle. 

Gardam's  Solar  Transit. — In  the  next  year  (1881),  Joseph 
Gardam,  of  Brooklyn,  N".  Y.,  patented  a  device,  in  which  the 
main  telescope  became  the  polar  axis,  upon  principles  very  sim- 

FIG.  122. 


Smith's  Improved  Solar. 

ilar  to  those  suggested  by  Pearsons.  As  shown  in  Fig.  123,  a 
flanged  collar  about  the  telescope  is  fixed  and  adjusted  to  the 
hub  of  the  telescope  by  means  of  angle-pieces  and  capstan-head 
screws.  A  semi-annular  ring,  with  its  attached  hour-circle  and 
declination-arc,  is  placed  over  this  collar,  and  held  in  any  posi- 
tion by  a  set-screw  that  travels  in  a  groove  provided  specially 
for  it.  In  revolving  on  this  collar-bearing  about  the  telescope, 


HISTORY    OF    SOLAR    SURVEYING    INSTRUMENTS. 


189 


the  declination-arc  took  up  so  much  room  that  the  length  of 
the  telescope-bubble  was  reduced  to  about  half  the  ordinary 
length. 

Saegmuller's  Solar  Transit. — In  1881  Geo.  ~N.  Saegmuller,  in- 
strument-maker, in  Washington,  D.  C.,  with  the  advice  of  cer- 
tain government  officials  on  the  Coast  Survey  (with  which  de- 
partment he  was  at  one  time  connected),  designed  and  patented 
a  telescopic  solar  attachment,  shown  in  Fig.  124,  mounted  upon 
an  instrument  of  his  own  make.  Mr.  Scott  has  discussed  the 
application  of  the  enlarged  attachment  to  mine-surveys;*  but 
only  the  use  of  the  smaller  model  in  solar  work  will  be  touched 

FIG.  123. 


Gardam's  Solar  Transit. 

upon  here.  The  attachment  is  fastened  to  the  top  of  the  main 
telescope  upon  a  polar  axis  very  similar  in  design  to  Schmoltz's 
modification  of  Burt,  and  is  kept  at  right  angles  to  the  main 
telescope  by  means  of  capstan-head  screws  operating  between 
the  plates.  The  angular  value  of  the  declination,  corrected 
for  refraction  and  hourly  change,  is  laid  off  on  the  vertical 
circle ;  the  transit-telescope  being  depressed  or  elevated  as  the 
declination  is  north  or  south.  The  solar  telescope,  being 
previously  adjusted  to  the  same  vertical  plane  with  the  main 
telescope,  is  then  brought  to  a  horizontal  position,  as  indicated 

*  Page  51. 


190  HISTORY    OF    SOLAR    SURVEYING    INSTRUMENTS. 

by  its  own  longitudinal  bubble.      This  arrangement,  as  already 
noted,  makes  it  possible  to  employ  the  vertical  or  latitude-circle 


FIG.  124. 


Saegmuller's  Solar  Transit. 

as  a  declination-arc.  The  two  telescopes  will  now  form  an 
angle  equal  to  the  declination,  and  the  inclination  of  the  solar 
telescope  to  its  polar  axis  will  be  equal  to  the  polar  distance  of 


HISTORY    OF    SOLAR    SURVEYING   INSTRUMENTS. 


191 


the  sun.  In  this  relative  position,  both  telescopes  are  now  so 
inclined  that  the  vernier  of  the  vertical  circle  indicates  the 
co-latitude  of  the  observer ;  and  thus,  on  rotating  the  instru- 
ment upon  its  vertical  axis  until  the  sun's  image  is  brought  into 
the  solar's  field  of  view,  the  transit-telescope  will  be  in  the  me- 

FIG.  125. 


Bell-Elliott-Eckhold  Omnimeter,  with  Saegmuller's  Solar. 

ridian.  In  recent  years  Elliott  Brothers,  of  London,  have  been 
adding  this  attachment,  provided  with  its  own  hour-circle,  as 
shown  in  Fig.  125,  to  the  Bell-Elliott  improved  Eckhold  Om- 
nimeter. 

In  1887  F.  E.  Brandis'  Sons,  of  Brooklyn,  K  Y.,  introduced  a 
modification  of  the  Saegmuller  solar  (Fig.  126),  in  which  the 


192 


HISTORY    OF    SOLAR    SURVEYING   INSTRUMENTS. 


small  telescope  is  "broken"  in  the  usual  way,  by  placing  a  prism 
between  the  objective  and  ocular.  For  this  device  is  claimed 
greater  convenience  in  sighting  the  sun,  as  the  eye-piece  is  al- 
ways at  the  side  of  the  instrument.  The  attachment  is  nicely 
balanced  by  placing  the  bubble  opposite  the  objective-end  of 
the  broken  telescope. 

Walter  Scott's  Solar  Attachment.— July  1,  1890,  Walter  Scott, 
of  Hot  Springs,  Dak.,  patented  an  attachment  of  the  Smith  type, 

FIG.  126. 


Brandis  Solar  Transit. 

which  he  claimed  could  be  readily  attached  to  any  ordinary 
transit-instrument.  This,  no  doubt,  is  too  great  a  claim.  The 
sighting-tube  having  a  single  smoked  lens  in  the  ocular,  and 
cross-hairs  only  at  the  objective-end,  rested  upon  a  base-plate 
pivoted  to  the  lower  end  of  one  of  the  standards.  The  latitude- 
arc  was  permanently  fixed  to  the  same  standard,  and  extended 
somewhat  beyond  at  the  upper  end  (Fig.  127),  terminating 
in  three  extra  perforations  for  the  reception  of  the  swivel- 


HISTORY    OF    SOLAR    SURVEYING   INSTRUMENTS. 


193 


block  of  the  tangent  screw.  At  the  lower  end  of  the  vernier- 
arm  of  the  declination-arc  is  a  prism,  or  mirror-reflector,  whose 
plane  of  reflection  is  at  45°  to  the  axis  of  the  sighting-tube, 
when  the  vernier  of  the  declination-arc  reads  0;  and  at  the 
upper  end  of  the  vernier-arm  there  is  a  convex  lens  to  converge 
the  sun's  rays  upon  the  reflector.  The  vernier  of  the  time- 
circle  is  a  part  of  one  of  the  collars  which  supports  the  sighting- 
tube.  What  has  been  said  concerning  the  operations  of  the 
Smith  solar  will  apply  generally  in  this  case :  the  main  differ- 

FIG.  127. 


Walter  Scott's  Solar  Attachment. 

ence  in  construction  being  the  rigidity  of  the  latitude-arc  in  the 
Scott  attachment. 

THE  DAVIS  SOLAR  TRANSIT. 

History  of  Origin,. — It  having  been  claimed  that  solar  instru- 
ments, or  attachments  for  solving  the  spherical  triangle  me- 
chanically, were  not  sufficiently  accurate  and  certain  in  their 
indications  to  be  used  in  transit-surveys,  a  committee  was  ap- 
pointed, in  1894,  by  the  Ohio  Society  of  Surveyors  and  Civil 
Engineers,  to  test  the  accuracy  of  solar  transits.  The  mem- 


194  HISTOKY    OF    SOLAR    SURVEYING    INSTRUMENTS. 

bers  of  this  committee  were  Charles  S.  Howe,  Professor  of 
Mathematics  and  Astronomy,  Case  School  of  Applied  Science, 
Cleveland ;  C.  H.  Burgess,  a  civil  engineer  of  Cleveland ;  and 
the  writer.  Mr.  Burgess  being  unable  to  give  to  the  matter 
his  personal  attention,  the  investigations  were  made  by  Prof. 
Howe  and  myself.  The  committee  succeeded  in  getting 
together  solar  instruments  of  all  the  prominent  makers  except 
one,  so  that  ample  opportunity  was  had  for  tests. 

The  report  of  the  committee  will  be  found  in  the  annual  vol- 
ume of  the  Society  for  1895.  It  states  the  conclusion  that 
"  errors  of  one  minute,  or  even  one  and  one-half  minutes  either 
way,  are  not  infrequent,  and  any  single  observation  would  be 
uncertain  to  this  extent."  The  observations  referred  to  fall 
within  an  arc  of  three  minutes.  The  committee  also  found  it 
essential  to  have  an  accurately  established  meridian  on  which 
first  to  test  the  solars ;  since,  when  the  sun  was  brought  into 
its  proper  relation  to  the  equatorial  lines,  the  true  meridian 
would  not  at  all  times  be  indicated.  In  order,  therefore,  to 
get  close  to  the  meridian,  the  instrument  must  first  be  set  on 
an  established  meridian,  and  the  actual  relation  of  the  sun's 
image  to  the  equatorial  lines  must  be  determined.  It  was  found 
that  the  sun's  image  would  be  sometimes  above  and  sometimes 
below  its  proper  central  position.  The  further  work  had  to  be 
done  in  accordance  with  that  determined  position.  We  con- 
cluded that  the  difficulty  arose  from  our  inability  to  adjust  the 
instrument  exactly.  From  experience  gained  in  these  tests,  the 
writer  became  satisfied  that  much  of  the  objection  of  the  profes- 
sion to  the  mechanical  solar  is  due  to  the  fact  that  additional 
adjustments  are  required,  that  the  adjustments  are- difficult  to 
make,  and  that  their  maintenance  is  a  matter  of  some  uncertainty. 

Believing  that  an  instrument  from  which  these  difficulties 
are  eliminated  would  be  desirable,  the  writer  began  experi- 
ments to  that  end;  and  the  first  instrument,  constructed  by 
Ulmer  &  Hoff,  Cleveland,  0.,  was  shown  before  the  Ohio  So- 
ciety of  Surveyors  and  Civil  Engineers  at  their  annual  meeting 
at  Dayton,  0.,  in  February,  1896.  This  transit-instrument  had 
a  vertical-  or  latitude-arc  and  a  telescope  capable  of  rotating  in 
a  sleeve  about  its  longitudinal  axis.  The  telescope  had  a  fixed 
object-end,  before  which  a  mirror  was  so  securely  attached  as 
to  partake  of  any  rotative  motion  of  the  telescope,  yet  capable 


HISTORY    OF    SOLAR    SURVEYING   INSTRUMENTS.  195 

of  revolving  about  an  axis  at  right  angles  with  the  line  of  col- 
limation.  In  1898,  the  writer  discovered  that  a  small  level 
placed  upon  the  transverse  axis  of  a  telescope  so  constructed 
would  enable  the  vertical-  or  latitude-arc  to  be  eliminated. 
For,  by  setting  off  the  latitude-angle  on  the  horizontal  limb, 
the  mirror,  reflecting  a  target,  could  be  placed  at  the  proper 
angle  with  the  optical  axis  of  the  telescope,  and  then,  by  rotating 
the  telescope  through  90°,  the  same  angle  could  be  transferred 
to  the  vertical  plane.  As  to  measuring  a  vertical  angle  on  the 
horizontal  limb,  it  is  not  intended  to  do  away  with  the  verti- 
cal-arc in  general  practice,  but  only  to  replace  the  latitude-  or 
vertical-arc  in  the  J.  B.  Davis  solar  transit  when  the  arc  is  only 
wanted  for  solar  work.  For  practical  reasons,  this  method  of 
setting  off  a  vertical  angle  is  not  applicable  for  latitudes  much 
lower  than  20° ;  but  these  are  much  lower  than  any  within  the 
boundaries  of  the  United  States.  Articles  describing  the 
J.  B.  Davis  solar  transit  have  appeared  in  the  Journal  of  the 
Association  of  Engineering  Societies,  November,  1896 ;  The  Col- 
liery Engineer,  July,  1897;  Engineering  News,  April  28,  1898; 
and  Mines  and  Minerals,  April,  1899.  It  was  patented  January 
21,  1897,  and  February  28,  1899. 

Description. — Figs.  128  and  129  represent  the  J.  B.  Davis 
solar  transit,  as  made  by  Ulmer  &  Hoff,  Cleveland,  0.,  without 
vertical-,  latitude-  or  declination-arc ;  all  angles  being  measured 
upon  the  horizontal  limb.  Fig.  128  shows  the  solar  transit 
with  the  reflector  attached,  and  Fig.  129  with  it  detached.  The 
solar  transit  is  constructed  with  or  without  a  vertical-arc,  as 
may  be  desired.  As  the  construction  of  a  solar  transit  without 
a  vertical-arc  is  a  new  departure,  the  method  of  operation  with- 
out the  arc  will  be  described ;  the  operation  with  a  vertical-arc 
will  then  be  obvious. 

The  transit-telescope  is  the  polar  axis  in  this  instrument, 
and  is  so  constructed  inside  a  sleeve  as  to  be  capable  of  ro- 
tating on  its  longitudinal  axis.  Its  object-end  is  fixed,  and  a 
reflector  is  securely  attached  to  it.  The  usual  vertical-  or 
latitude-arc  is  dispensed  with ;  but  a  level  is  placed  upon  the 
transverse  axis  of  the  telescope.  The  reflector  is  so  con- 
structed as  to  be  capable  of  rotating  with  its  frame  about  the 
line  of  collimation  of  the  telescope  as  an  axis,  and  also  of  re- 
volving on  an  axis  in  its  own  plane  at  right  angles  to  that 

14 


196 


HISTORY    OF    SOLAR    SURVEYING    INSTRUMENTS. 


line ;  so  that  by  sighting  to  a  target  the  reflector  may  be  placed 
in  proper  angular  relation  to  the  line  of  collimation  in  each 
meridian  and  latitude  observation.  This  reflector-construc- 
tion, together  with  the  rotating  transit-telescope,  results  in 


FIG.  128. 


J.  B.  Davis  Solar  Transit,  Keflector  Attached. 

doing  away  with  the  maintenance  of  all  solar  adjustments. 
Thereby,  as  the  transit-telescope  is  used  for  solar  work,  not 
only  is  the  accuracy  of  the  instrument  increased,  but  the  cer- 
tainty of  its  indications  as  well;  because  adjustments  of  special 
solar  apparatus  are  difficult  to  make,  are  sensitive,  and  conse- 


HISTORY    OF    SOLAR    SURVEYING   INSTRUMENTS. 


197 


quently  easily  disturbed.  All  solar  transits  heretofore  con- 
structed require  the  maintenance  of  certain  adjustments  ad- 
ditional to  those  of  the  engineer's  and  surveyor's  transit ;  and 
the  majority  have  separate  latitude-  and  declination-arcs.  In 


FIG.  129. 


J.  B.  Davis  Solar  Transit,  Keflector  Detached. 

this  solar  these  arcs  are  dispensed  with,  and  all   angles  are 
measured  on  the  horizontal  limb  of  the  transit. 

At  the  eye-piece  end  of  the  telescope  is  placed  the  cross-hair 
ring,  or  diaphragm,  provided  with  the  usual  vertical  and  hori- 
zontal transit-hairs,  AB  and  CD,  and  the  two  solar  hairs  EF 


198 


HISTORY    OF    SOLAR    SURVEYING    INSTRUMENTS. 


and  GrH,  Fig.  130.  The  small  circle  between  the  solar  or 
equatorial  hairs  represents  the  sun  in  the  field  of  view.  Fig. 
130  shows  the  diaphragm  in  its  normal  position  for  terrestrial 
work.  The  line  of  collimation  can  be  adjusted  on  a  fixed 
point  by  rotating  the  telescope  in  its  sleeve,  as  an  engineer's 
wye-level  on  its  wyes.  The  solar  hairs  and  rotating  telescope 
are  a  convenience,  even  when  only  terrestrial  work  is  required 
of  the  transit;  for  the  solar  hairs  can  be  used  for  stadia-work, 
and  the  operator  can,  by  rotating  the  telescope,  quickly  provide 
himself  with  a  single  hair  for  either  transit-  or  level- work.  At 
the  eye-end  of  the  telescope  there  is  a  shaded  glass  slide  for 


Transit  and  Solar  Cross-Hairs. 

use  in  observing  the  sun.  A  diagonal  prism  is  not  required, 
as  the  eye-piece  is  elevated,  in  the  position  most  favorable  and 
convenient  for  the  observer.  The  needle  and  the  time-gradua- 
tions on  the  telescope  act  jointly  as  a  finder,  to  bring  the  image 
of  the  sun  within  the  field  of  view.  When  the  transit  is  not 
required  for  solar  work,  the  reflector  can  be  removed  from  the 
object-end  of  the  telescope,  and  the  telescope  secured  in  its 
normal  position  by  a  set-screw.  The  central  cross-hair  is  then 
vertical,  and  the  telescope  is  firmly  fixed  in  its  sleeve. 

The  advantages  obtained  in  this  solar  transit  are :  (1)  sim- 
plicity ;  (2)  the  use  of  but  one  telescope  for  solar  and  transit 
work;  (3)  the  omission  of  the  usual  declination-  and  latitude- 
arcs,  the  graduated  horizontal  limb  of  the  transit  serving  their 


HISTORY    OF   SOLAR    SURVEYING   INSTRUMENTS. 


199 


purpose;  (4)  the  elimination  of  the  maintenance  of  all  adjust- 
ments of  solar  parts ;  (5)  the  obviation  of  all  necessity  of  coun- 
terpoising the  solar  parts  or  attachments — the  reflector  weigh- 
ing no  more  than  the  sun-shade;  (6)  the  absence  of  projecting 
parts  liable  to  injury. 

With  this  instrument,  solar  work  in  keeping  with  the  accu- 


FIG.  131. 


/ 


^ 


x"  '  R 
s 

NO-'    --' 
/>'  .-•' 

R£ 

<£    ..SG* 

/ 

>e^TT 

/ 
/     f 

/ 

^^^^ 

C^  A 

^X4 

/ 


%^s 


V^w 


V 
o^ 


^ 

%^ 


°X). 


NS,  Line  of  collimation  of  the  telescope  and  polar  axis.  EQ,  Equator.  CC1, 
Transit-telescope.  RR1,  Reflector.  Rc,  Position  of  the  image  in  the  re- 
flector-plane. Cs,  Center  of  revolution  of  the  transit-telescope.  T,  Target. 
T1,  Stationary  sighting-point.  T2,  Movable  sighting-point.  Angle  A,  South 
polar  distance  of  the  sun.  The  declination  of  the  sun,  corrected  for  refrac- 
tion, =  20°. 

racy  of  an  engineer's  transit  can  be  done,  if  the  proper  hours 
of  the  day  for  doing  it  are  selected.  The  writer  is  satisfied 
that  solar  work  requiring  the  closest  possible  results  can  only 
be  done  in  the  middle  of  the  forenoon  or  afternoon.  Close 
work  cannot  be  done,  and  need  not  be  attempted,  with  any 
solar,  very  near  noon ;  because  an  error  then  made  in  setting  off 


200 


HISTORY    OF    SOLAR    SURVEYING   INSTRUMENTS. 


the  exact  latitude  or  declination  is  considerably  multiplied  in 
the  azimuth.  A  want  of  knowledge  on  this  point  has  led  many 
into  error,  and  some  to  doubt  the  efficacy  of  solar  work  en- 
tirely, under  the  wrong  presumption  than  any  hour  of  the  day 
is  equally  favorable  to  such  work. 

Operation. — Fig.  131  illustrates  the  target-sighting  method  of 
setting  the  reflector  in  its  proper  relation  to  the  line  of  colli- 

FIG.  132. 


\ 


s 


H 


N       ...*f 

\ 

\ 

a 


/  / 

/     / 

I  /  ' 


I  / 

/  s 

\ 


\ 


O 


\ 


\ 


R' 


HO,  A  horizontal  plane.  PP1,  Line  of  collimation  of  the  transit.  KB1,  Be- 
flector-plane.  EQ,  Line  from  the  point  Q  at  right  angles  to  the  line  of  col- 
limation. QDN  and  QD^,  Declination-lines. 


mation  for  a  meridian  or  latitude  observation,  and  will  be  re- 
ferred to,  as  the  operation  of  the  instrument  is  described  in 
detail. 

The  optical  axis  of  the  telescope  CC1,  the  sighting-point,  T1 
or  T2,  and  the  image  of  the  same  in  the  reflector  RE,1,  are  all 
in  the  same  horizontal  plane  when  the  image  of  T1  or  T2  is 
thrown  into  the  line  of  collimation.  When  the  reflector  is 
placed  at  an  angle  of  45°  to  the  line  of  collimation,  the  line  of 


HISTORY    OF    SOLAR    SURVEYING   INSTRUMENTS.  201 

sight  of  the  telescope  is  deflected  90  °,  and  will  represent  the 
equator ;  and  when  the  reflector  is  placed  at  an  angle  to  the 
line  of  collimation  of  45°  plus  or  minus  one-half  the  declina- 
tion of  the  sun  (according  as  the  declination  is  north  or  south), 
the  line  of  sight  of  the  telescope  will  be  deflected  by  an  angle 
equal  to  the  south  polar  distance  of  the  sun.  The  target,  as 
indicated  in  Fig.  131,  has  two  sighting-points,  T1  and  T2;  T1 
alone  is  used  in  setting  off  the  latitude  ;  T1  and  T2  are  together 
used  in  setting  the  reflector  in  a  meridian  observation,  as  will 
hereafter  be  explained.  The  target  T  remains  stationary  and 
is  set  at  right  angles  to  a  line  drawn  from  the  target-point  T1 
to  the  transit-center;  therefore,  when  the  angle  A  is  90°,  the 
distance  T1  T2  =  CE  Rc.  When  the  angle  A  becomes  more 
or  less  than  90°,  the  distance  T1  T2  must  be  reduced,  so  as  to 
equal  the  perpendicular  distance  of  Rc  from  the  line  CR  T1. 
To  provide  for  this,  the  sighting-point  T2  is  movable  on  the 
target,  and  an  index-point  and  graduations  enable  the  operator 
to  set  it  in  proper  position  for  any  angle  A.  The  following 
statement  will  show  the  principles  on  which  the  operation  of 
the  solar  is  based. 

Place  the  line  of  collimation  of  the  transit-telescope  PP1  (Fig. 
132)  in  the  horizontal  plane  HO,  and  intersecting  the  reflecting- 
plane  RR1  at  Q,  with  the  reflecting-plane  so  placed  (at  45°)  that 
any  point  E  situated  in  the  horizontal  plane  and  in  a  line  at  right 
angles  to  the  line  of  collimation  from  the  point  Q  will  be  re- 
flected along  the  line  of  collimation ;  or,  again,  in  such  other 
position  that  reflection  in  the  line  of  collimation  will  take  place 
from  any  point,  such  as  D  ~N  and  DXS,  lying  in  the  horizontal 
plane  and  situated  either  to  the  right  or  left  of  the  point  E  and 
in  the  line  from  the  point  Q  that  makes  an  angle  with  the  line 
EQ  equal  to  the  declination  of  the  sun  at  the  time.  The  re- 
flecting-plane will  now  be  perpendicular  to  the  horizontal 
plane,  in  which  the  line  of  collimation  lies ;  and  the  horizontal 
angle  between  the  line  of  collimation  and  the  intersection  of 
the  two  planes  will  be  such  as  the  declination  of  the  sun  at  the 
time  of  observation  may  require. 

If,  then,  keeping  this  angle  unchanged,  the  line  of  collima- 
tion PP1  be  inclined,  as  in  Fig.  133,  to  the  horizontal  plane 
HO,  at  an  angle  equal  to  the  latitude  of  the  place,  P2L  (in  the 
manner  to  be  presently  described),  and  the  reflector-plane  be 


202  HISTORY    OF    SOLAR    SURVEYING   INSTRUMENTS. 

rotated  about  that  line  as  an  axis,  the  sun  can  be  followed  in 
its  passage  from  east  to  west,  in  case  the  line  of  collimation  is 
in  the  plane  of  the  meridian.  The  line  of  collimation  may  be 
brought  into  that  plane  by  a  horizontal  circular  motion  about 
QC,  the  vertical  axis  of  the  instrument,  at  right  angles  to  the 
horizontal  plane.  At  the  same  time  the  line  of  collimation, 
and  with  it  the  reflecting-plane,  is  rotated  about  itself  as  an 
axis,  until  the  center  of  the  image  of  the  sun  is  seen  exactly 
in  the  line  of  collimation.  The  line  of  collimation  will  then  be 
in  the  meridian  plane  of  the  observer. 

FIG.  133. 


Again,  returning  to  Fig.  131,  let  it  be  understood  that  in  the 
operation  of  this  instrument  the  optical  axis  of  the  telescope, 
or  the  line  of  collimation,  is  what  is  termed  the  polar  axis  in 
other  solar  instruments ;  so  that  any  line  perpendicular  to  the 
optical  axis  from  a  point  in  the  reflector-plane  at  its  intersection 
with  the  optical  axis  of  the  telescope  produced  will  be  in  the 
plane  of  the  equator.  The  sun  in  its  position,  on  one  or  the 
Other  side  of  the  equator,  in  its  varied  positions  of  declination 
throughout  the  year,  will  be  represented  by  the  correspond- 
ingly varied  horizontal-angular  position  of  the  target  as  sighted 


HISTORY    OF    SOLAR    SURVEYING   INSTRUMENTS.  203 

to  in  each  observation.  This  varied  position  of  the  target  with 
reference  to  the  aforesaid  equatorial  line  is  determined  by  the 
angle  A,  which  varies  with  the  sun's  declination.  It  will  thus 
be  seen  that  the  target  is  made  to  bear  the  same  relation  to  the 
optical  axis  of  the  telescope,  and  the  aforesaid  line  perpendicular 
thereto,  as  the  sun  bears  to  the  polar  axis  and  equatorial  line 
at  the  time  of  observation ;  and  that  if  the  telescope  be 
dipped,  with  reference  to  a  horizontal  plane,  sufficiently  to 
conform  to  the  position  of  the  earth's  axis  at  the  point  of  ob- 
servation, the  sun's  image  can  only  be  seen  in  the  optical  axis  of  the 
telescope  when  the  telescope  has  been  brought  into  the  plane  of  the 
meridian. 

To  Set  the  Telescope  to  the.  Latitude- Position. — 1.  See  thatthe  usual 
transit  adjustments  are  carefully  made.  Loosen  the  set-screw 
which  passes  through  an  arm  of  the  telescope-axis  and  engages 
the  telescope,  so  that  the  telescope  can  be  rotated  in  its  sleeve 
until  the  solar  lines  have  become  vertical.  When  the  rotation 
has  been  made,  secure  the  telescope  by  the  same  set-screw. 
Clamp  the  solar  reflector-frame  to  the  object-end  of  the  tele- 
scope, placing  it  so  that  the  reflector  will  be  approximately  in 
a  vertical  plane  and  parallel  to  the  line  of  collimation,  so  as  not 
to  obstruct  the  view  through  the  telescope.  Place  the  transit- 
center  vertical  by  means  of  the  plate-levels  and  the  telescope- 
level  ;  and  then,  while  the  telescope  is  level,  sight  a  target  (at 
any  convenient  distance,  20  to  200  feet  from  the  transit)  with 
the  stationary  sighting-point  T1  on  both  the  central  vertical  and 
the  horizontal  cross-hairs,  and  the  movable  sighting-point  T2  on 
the  horizontal  cross-hair  only.  (See  Fig.  131.) 

2.  Observe  the  reading  of  the  horizontal  limb,  and  then  set 
off  on  that  limb  an  angle  equal  to  the  latitude  of  the  place  of 
observation ;  and,  with  the  telescope  still  horizontal,  by  rotat- 
ing the  reflector  about  its  own,  then  vertical,  axis,  bring  the 
image  of  the  target-point  T1  into  the  line  of  collimation  of  the 
telescope.     (See  Fig.  134.) 

3.  Without  changing  the  angle  made  by  the  reflector  with  the 
line  of  collimation,  return  to  the  first  reading  of  the  limb ;  the 
telescope  will  then  again  be  directed  to  the  target-point  T1. 
Loosen  the  set-screw  before  referred  to,  and  rotate  the  telescope 
90°,  securing  it  by  the  set-screw  in  this  position.     Dip  the 
telescope  until  the  reflected  image  of  the  target-point  T1  appears 
in  the  line  of  collimation ;  and  then  bring  the  bubble  of  the 


204  HISTORY    OF    SOLAR    SURVEYING    INSTRUMENTS. 

transverse-axis  level  to  a  central  position.     (See  Fig.  135.)    The 
telescope  is  now  dipped  to  the  required  latitude-angle,  and  the 
axis-level  enables  the  operator  at  any  time  to  restore  the  tele- 
scope quickly  and  accurately  to  the  proper  latitude-position. 
To  Determine  the  Meridian. — 1.  Again  place  the  solar  hairs 

FIG.  134. 


Showing  the  Latitude-Angle  in  a  Horizontal  Plane.  T,  Target.  T1,  Stationary 
sighting-point.  T2,  Movable  sighting-point.  C  C1,  Transit-telescope  in  two 
horizontal  positions.  Cr,  Center  of  horizontal  revolution  of  the  transit-tele- 
scope. E,  Eeflector.  LL1,.  Latitude  angle.  T1,  Cr  and  the  image  of  T1  in  E 
are  in  a  horizontal  plane. 

perpendicular,  remembering  that  the  transit-telescope  will  be 
directed  to  the  target-point  T1,  when  the  transit-limb  is  made 
to  indicate  the  first  angle  read  in  the  operation  of  dipping  the 
telescope  to  the  latitude  position.  Now,  set  off  an  angle  equal 
to  90°,  plus  or  minus  the  corrected  declination  of  the  sun  at 
he  time  of  observation,  according  as  the  sun  is  north  or  south 

FIG.  135. 


Showing  the  Latitude- Angle  in  a  Vertical  Plane.  T,  Target.  T1,  Stationary 
sighting-point.  C  C1,  Transit-telescope.  Cr,  Center  of  revolution  of  the 
transit-telescope.  E,  Eeflector.  L  L1,  Latitude  angle.  B  B1,  Transverse-axis 
level.  T1,  Cr  and  the  image  of  T1  in  E  are  in  a  vertical  plane. 

of  the  equator.  This  angle  is  the  south  polar  distance  of  the 
sun,  and  is  indicated  as  angle  A  in  Fig.  131.  With  the  tele- 
scope level,  place  the  reflector  in  such  a  position  that  the  image 
of  the  target-point  T2  will  appear  exactly  in  the  line  of  collima- 
tion  of  the  telescope.  (The  target-point  T2  is  sighted  to,  for  the 
purpose  of  allowing  for  the  parallax  due  to  the  reflector's  being 
at  the  object-end  of  the  telescope,  and  not  at  the  transit-center ; 
and  the  distance  T1  T2  is  controlled  by  the  angle  A,  as  before 
explained.)  By  this  operation,  the  plane  of  the  reflector  is 


HISTORY    OF    SOLAR    SURVEYING    INSTRUMENTS.  205 

made  vertical,  and  at  the  same  time  its  intersection  with  the 
horizontal  plane  of  the  collimation  of  the  telescope  will  be  at 
such  a  horizontal  angle  with  the  collimation  as  the  declination 
of  the  sun  at  the  time  of  observation  requires.  (See  Fig.  131.) 

2.  Having  now  placed  the  reflector  in  proper  angular  relation 
to  the  line  of  collimation,  turn  the  object-end  of  the  telescope 
south;    dip  it  from   a  horizontal  position  by  an  angle   equal 
to  the  latitude  of  the  place  of  observation,  by  means  of  the 
transverse-axis  level  (previously  set  to  indicate  the  proper  lati- 
tude); and  securely  clamp  the  telescope.     Loosen  the  set-screw, 
so  that  the  telescope  rotates  in  its  sleeve.     It  will  be  seen  that 
the  sun  can  then  be  followed  in  its  daily  motion.     Rotate  the 
telescope  in  its  sleeve,  and  at  the  same  time  turn  the  whole 
instrument  horizontally,  until  the  sun  appears  exactly  between 
the  solar  hairs,  and  the  perpendicular  hair  approximately  bi- 
sects it.     Then  firmly  clamp  the  transit-center.      The  telescope 
witt  then  be  in  the  true  meridian. 

3.  Bring  the  telescope   back  to  its  normal  position  in  its 
sleeve,  and  secure  it  by  the  set-screw.     Unclamp  the  telescope- 
axis  and  fix  the  meridian-line  by  suitable  points.     In  doing  this 
the  reflector  is  undamped  and  placed  parallel  to  the.  line  of 
collimation.     In  this  position  it  forms  no  obstruction  whatever 
to  the  line  of  sight. 

To  Determine  the  Latitude. — 1.  Place  the  reflector  in  proper 
angular  relation  to  the  line  of  collimation  (as  in  the  instruc- 
tions for  determining  the  meridian),  so  as  to  reflect  into  that 
line  the  sun's  image  when  at  noon-declination.  Rotate  the 
telescope  90°  in  its  sleeve,  and  secure  it  by  the  set-screw. 

2.  Dip  the  telescope,  and  follow  the  sun  until  it  has  attained 
its  greatest  altitude.     Then  set  the  latitude-  or  transverse  axis 
level  in  a  horizontal  position,  in  order  that  the  telescope  may 
be  returned  to  the  proper  latitude-position  whenever  desired. 

3.  To  read   the    latitude-angle   from  the  transit-limb,  first 
place  the  telescope  in  the  vertical  plane  passing  through  the 
target-point  T1,  by  returning  to  the  same  reading  of  the  limb 
as  indicated  when  the  target  was  first  sighted,  in  the  operation 
of  setting  the  reflector  to  its  declination-position.     Still  retain- 
ing the  telescope  in  its  established  latitude-position,  change  the 
reflector  so  as  to  throw  the  image  of  the  target-point  T1  into 
the  line  of  collimation.     Now  place  the  telescope  in  a  hori- 
zontal plane,  rotating  it  90° ;  and  then  move  it  horizontally 


206  REMARKS    ON    MINE-SURVEYING    INSTRUMENTS. 

until  the  target-center  is  again  seen  reflected  in  the  line  of  col- 
limation.  (See  Figs.  134  and  135.)  Then  read  off  the  latitude 
from  the  transit-limb. 


Remarks  on  Mine-Surveying  Instruments, 

with  Special  Reference  to  Mr.  Dunbar  D.  Scott's  Paper 

on  their  Evolution,  and  its  Discussion. 

BY  H.    D.    HOSKOLD,   INSPECTOR    GENERAL  OF  MINES   OF  THE   ARGENTINE 
REPUBLIC,   BUENOS  AIRES,   S.  A. 

(Canadian  Meeting,  August,  1900.) 

SYNOPSIS. 
I.  INSTRUMENT-PARTS  AND  IMPLEMENTS. 

Cross-hairs ;  Stadia-measurement ;  Fineness  of  Graduation  ;  Cylindrical  Gradu- 
ation ;  Nonius  ;  Vernier  ;  One  Vernier  or  two  ;  Leveling-Screws  ;  Troughton 
&  Simms'  Shifting  Tripod-Head  ;  Hoskold's  Shifting  Tripod-Head  ;  Hoskold's 
Extensible  Tripod  ;  Electric  Lamp  ;  Plumb-lines ;  Chain. 

II.  INSTRUMENTS. 

Compass  (Mine-compass  of  1518,  Compass  of  1541,  and  Agricola's  of  1556,  Voig- 
tel's  Setz-compass,  Circumferentor,  Stanley's  Hedley  Dial,  Compass  on  Tele- 
scope, Hanging  Compass,  Lack  of  Precision)  ;  Plane-table ;  Octant  and 
Quadrant;  Theodolite  and  Transit  (Evolution  of  the  Theodolite,  Scott's 
Tachymeter,  Hoskold's  Engineer's  Theodolite,  Angleometer,  Precision  of 
Mine-Theodolites). 

I.  INSTRUMENT-PARTS  AND  IMPLEMENTS. 
Cross-Hairs. — Mr.  Scott*  says  Lean's  dial 

"might  also  have  been  provided  with  a  diaphragm  and  cross-hairs  ;  for  Huygens 
discovered  that  any  object  placed  in  the  common  focus  of  the  two  lenses  of  a 
Kepler  telescope  (1611)  appeared  as  distinct  and  well  defined  as  any  distant  body. 
Following  this  established  theory,  in  1667  Jean  Picard,  Marquis  Malvasia  and 
others  crossed  silken  fibers  in  the  common  focus  of  their  astronomical  instruments." 

If  by  this  Mr.  Scott  means  that  Huygens  and  Picard  first 
devised  and  applied  cross-hairs  to  the  focus  of  the  telescope, 
the  writer  cannot  agree  with  him.  Huygens  did  not  describe 
"  his  telescope  without  tubes  until  1684,  in  his  Astroscopia  Com- 
pendiaria."-f  Moreover,  it  is  recorded  that  the  English  astrono- 
mer, Gascoigne,f 

*  Page  19.          f   Universal  Biography,  Mackenzie,  p.  968.  J  Ibid.,  p.  564. 


REMARKS    ON    MINE-SURVEYING   INSTRUMENTS.  207 

' '  was  the  first  who  placed  crossed  filaments  at  the  common  focus  to  mark  the  cen- 
ter, axis  or  line  of  collimation  of  the  telescope,  enabling  that  line  to  be  directed 
towards  the  object  to  be  observed." 

In  another  place  it  is  stated  that  this  invention  took  place  in 
1640.*  Picard,  originally  a  priest,  did  not  become  an  assistant 
astronomer  to  Gassendi  earlier  than  1645. 

Stadia-Measurement. — If  Mr.  Brough  and  Mr.  J.  L.  Van 
Ornumf  intend  to  convey  the  idea  that  James  Watt,  in  1770- 
1771,  was  the  first  to  discover  special  means  for  the  determina- 
tion of  distances  upon  the  surface,  without  direct  measurement 
by  a  chain  or  other  linear  measurer,  then  they  have  fallen  into 
a  grave  error;  for,  it  is  recorded  that  Gascoigne  "invented  the 
micrometer,  which  by  measuring  the  apparent  size  of  the  im- 
age ascertained  the  angle  subtended  by  the  object."! 

Gascoigne's  two  inventions — placing  cross-hairs  in  the  focus 
of  the  telescope,  and  the  micrometer — by  which  the  telescope 
was  first  adapted  to  observing  exactly  the  position  and  apparent 
size  of  the  heavenly  bodies  and  of  "  distant  objects  on  the  earth, 
are  the  most  important  improvements  which  have  been  made  in 
astronomical  and  geodetical  instruments  since  the  invention  of 
the  telescope.  Their  date  lies  somewhere  between  1638  and 
1643. "§  Again,  it  is  declared]!  that  the  micrometer  of  Gascoigne 
"may  be  considered  the  prototype  of  our  best  spider's  line  mi- 
crometer." Gascoigne  also  measured  the  diameter  of  the  sun 
and  moon  and  the  angular  distances  of  the  stars  in  the  Pleiades 
by  his  micrometer  in  1640-Tf  Oughtred  also  received  a  letter 
from  Gascoigne  in  1640-41,  referring  to  his  newly  invented 
micrometer.**  Townleyft  saJs  of  Gascoigne: 

' '  Before  our  late  Civil  Wars,  he  had  not  only  devised  an  Instrument  of  as  great  a 
power  as  M.  Auzout's,  but  had  also  for  some  Years  made  use  of  it,  not  only  for 

*  Hoskold  upon  Ancient  and  Modern  Surveying  and  Surveying  Instruments,  Trans. 
Am.  Soc.  Civ.  E.,  vol.  xxx.,  pt.  ii.,  pp.  135-154  (1893). 

f  Page  70. 

J  Universal  Biography,  Mackenzie,  p.  564,  and  Pearson's  Astronomy,  pp.  92-93, 
1829. 

g   Universal  Biography,  Mackenzie,  p.  564,  and  Phil.  Trans.,  1737. 

||  Pearson's  Astronomy,  p.  93,  vol.  iii.,  1829. 

1f  Flamsteed's  Prolegomena,  Historic  Ccdestw,  vol.  iii.,  p.  95. 

**  Phil.  Trans.,  vol.  xlviii.,  p.  191,  1753. 

ft  Phil.  Trans.,  No.  25/p.  457,  May,  1667,  and  Pearson's  Astronomy,  p.  92,  vol. 
iii.,  1829. 


208  REMARKS    ON    MINE-SURVEYING    INSTRUMENTS. 

taking  the  Diameter  of  the  Planets,  and  Distances  upon  Land  ;  but  had  farther 
endeavour' d,  out  of  its  preciseness,  to  gather  many  Certainties  in  the  Heavens ; 
amongst  which  I  shall  only  mention  one,  viz.,  The  finding  of  the  Moons  Distance." 

The  micrometer  or  distant-measurer  of  Gascoigne  was  capable 
of  marking  40,000  divisions  in  a  foot  with  the  help  of  two  in- 
dexes. The  result  was  that  he  could  measure  an  object  to  a 
single  second  of  arc.*  The  micrometer  employed  by  Auzout 
and  Picard  only  measured  from  20  to  30,000  parts  of  a  foot.f 
The  words  just  quoted, "  distances  upon  land,"  are  exceedingly 
important  for  the  purpose  of  determining  the  question  under 
discussion;  for,  although  James  Watt  may  have  made  such  an 
invention  in  1771  as  that  attributed  to  him,  still  the  authorities 
quoted  place  it  beyond  doubt  that  Gascoigne  was  the  first  Eng- 
lishman to  invent  and  apply  a  distant-measurer. 

Fineness  of  Graduation. — Mr.  Scott  declines  to  continue  the 
discussion  of  the  relative  merits  of  the  minute-graduations  as 
compared  with  finer  divisions ;  but  the  writer  is  of  opinion  that 
after  the  demonstration  given  by  him{  the  minute-division 
theory  is  untenable.  As  Mr.  Scott  has  pointed  out,§  if  we 
assume  an  isolated  case,  and  say  that  there  would  be  an  error 
of  30"  on  a  line  of  100  feet,  the  deviation  would  be  too  insig- 
nificant to  be  noticed ;  and,  although  the  proposition  is  ingeni- 
ously put,  still  it  is  not  stating  the  whole  case.  Taking  it  for 
granted,  as  Mr.  Scott  says,  that  a  minute-vernier  can  be  read 
without  greater  error  than  30",  the  error  would  be  a  continuous 
one,  frequently  repeated,  and  increasing  according  to  the 
number  of  lines  in  the  survey  minus  one ;  and  if  the  distances 
were  equal  and  the  error  angle  had  the  same  sign,  we'  should 
be  tracing  a  slow  curve,  and  the  total  deviation-error  in  arc 
would  equal  the  number  of  lines  minus  one  multiplied  by  30". 
The  same  principle  is  involved  in  an  underground  survey,  with 
the  difference  that  the  length  of  the  lines  would  vary.  To  be 
sure,  the  error-angle  would  sometimes  be  a  positive  and  at 
others  a  negative  quantity,  and  for  this  reason  some  engineers, 
surveyors  and  mathematicians  have  stated  that  the  one  would 
balance  the  other.  But  they  forget  that  such  an  effect  could 

*  Pearson's  Astronomy,  p.  92,  vol.  iii.,  1829. 
t  Phil.  Trans.,  No.  21,  p.  373,  Jan.,  1666. 
t  Page  114.  \  Page  ]27. 


REMARKS    ON    MINE-SURVEYING   INSTRUMENTS.  209 

not  result  unless  the  lengths  of  the  lines  were  equal,  and  the 
error-angle  always  had  a  positive  and  negative  effect  alternated, 
or  in  reciprocal  succession,  conditions  which  could  not  occur. 
There  is  no  excuse  or  reason  in  advocating  that,  because  some 
careless  persons  elect  to  use  a  rough  line-measuring  instrument, 
the  divisions  of  a  theodolite-vernier  should  be  no  finer  than  a 
minute  of  arc. 

Cylindrical  Graduation. — Messrs.  Wittstock's  idea  of  putting 
the  graduation  on  the  edge  of  vertical  circles,  instead  of  upon 
the  flat  side,  is  not  new.*  Instruments  were  divided  on  the 
cylindrical  edge  some  thirty  years  since  by  Troughton  & 
Simms,  of  London.  The  writer  once  inspected  in  their  noted 
establishment  various  instruments  of  this  kind  which  had  been 
constructed  for  use  in  the  great  Indian  Survey.  The  mathe- 
matical instrument-maker  Cooke,  of  York,  adopted  the  same 
plan  many  years  since  for  his  new  form  of  transit-theodolite, 
Fig.  136. 

Nonius. — The  reading  of  fractional  parts  of  a  degree  on  astro- 
nomical and  surveying  instruments  was  much  facilitated  by  the 
invention  of  Nonius  or  Nunez, f  about  1542;  but  his  plan  gave 
place  to  the  more  accurate  mode  of  Digges.J  Tycho  Brahe  is 
said  to  have  adopted  this  invention — i.e.,  the  subdivision  of  a 
degree  into  fractional  parts  by  means  of  diagonal  lines — and 
applied  it  to  his  quadrant,  dividing  it  into  minutes,  somewhere 
between  1566  and  1570.§  This  system  was  employed  in  Ger- 
many for  a  considerable  time  afterwards. 

Vernier. — The  plan  of  subdividing  by  diagonal  lines  was 
finally  superseded  about  1631-2  by  the  more  accurate,  con- 
venient and  facile  system  of  subdividing  introduced  by  Vernier, 
a  method  that  has  not  been  superseded  nor  ever  will  be ;  except 
for  excessively  fine  readings,  which  can  only  be  conveniently 
obtained  by  the  use  of  the  micrometrical  microscopes  applied  to 
the  larger  instruments. 

*  Trans.,  xxix.,  1001,  1899. 

t  The  system  is  explained  in  the  book  of  Nonius  entitled  De  Crepusculis. 

J  Alee  Sen  Scales  Mathematical,  Thomas  Digges,  London,  1573.  [See  also  pages 
122  and  123,  for  an  illustration  and  the  history  of  this  method  of  subdividing 
angles,  the  so-called  diagonal  scale,  or  method  of  transversals.] 

\  Universal  Biography,  Mackenzie,  p.  854.  [Brahms  great  quadrant  of  14  cubits, 
about  19  feet,  in  radius,  was  built  at  Augsburg  in  1569.  See  Dreyer's  Tycho 
Brahe,  1891,  p.  32.] 


210 


REMARKS    ON    MINE-SURVEYING    INSTRUMENTS. 


One  Vernier  or  Two. — The  one  double  vernier  described  by 
Messrs.  Wittstock*  is  much  less  satisfactory  than  two  single 
verniers  placed  on  opposite  sides  of  a  circle ;  simply  because 
the  latter  plan  affords  the  means  of  taking  an  average  of  read- 
ings from  two  parts  of  the  circle  at  the  same  time,  so  as  to  re- 
duce the  effect  of  eccentricity  and  errors  of  graduation.  But 
with  one  vernier,  although  double,  as  proposed  by  Messrs. 

FIG.  136. 


Cooke's  Theodolite. 

Wittstock,  such  errors,  if  they  exist,  must  remain  without  cor- 
rection. Possibly,  however,  this  objection  may  be  met  by  the 
statement  that  such  refinement  is  not  required  for  mine-surveys. 
The  best  English  mathematical  instrument-makers,  writers 
and  other  scientific  men  have  long  since  recognized  the  prin- 
ciple just  noted,  and  have  provided  means  for  the  reduction  of 
such  errors  to  a  minimum.  Generally,  therefore,  three  equi- 
distant verniers  are  provided  for  the  horizontal  circle  of  theo- 

*  Page  139. 


REMARKS    ON    MINE-SURVEYING   INSTRUMENTS.  211 

dolites  from  6  to  8  inches  in  diameter.  As  far  back  as  1858 
three  verniers  were  attached  to  the  vertical  circle  of  the  miner's 
transit-theodolite,  Fig.  74;*  and  the  same  plan  has  been  con- 
tinued and  applied  to  the  horizontal  circle  of  Fig.  75, f  also  with 
the  addition  of  double  readings  to  the  vertical  semicircles. 

Leveling-Screws. — With  reference  to  the  mode  of  leveling-up 
surveying  and  spirit-level  instruments,  Mr.  Stanley  admits  that 
there  is  a  "  strain  put  upon  the  axis  of  the  instrument  by  the 
use  of  four  leveling-screws,"  but  he  considers  it  "  unimportant." 
It  is  nevertheless  certain  that  anything  defective  in  the  con- 
struction of  an  instrument  tends  to  disturb  or  destroy  its  abso- 
lute stability ;  and,  for  that  reason,  any  defect,  however  small, 
should  be  removed.  The  strain  referred  to  is  augmented  when 
the  instrument  is  top-heavy.  The  four  conjugate  screws 
formerly  attached  to  theodolites  and  spirit-levels,  and  admired 
so  much  by  the  old  school  in  England,  until  a  new  practice  was 
introduced,  were  placed  between  the  parallel  leveling-plates, 
with  so  short  a  leverage  from  the  vertical  axis  of  the  instrument 
to  the  center  of  the  screws  that  they  never  admitted  of  a  facile 
and  permanent  mode  of  leveling.  Especially  has  this  been  felt 
when  surveys  were  made  upon  severely-inclined  land;  so  that 
the  difficulties  have  led  inexpert  persons  to  introduce  the  Hoff- 
man patent  joint  attachment,  as  an  additional  means  to  assist 
in  leveling  with  four  screws.  However,  in  the  hands  of  expert 
surveyors,  this  appendage  is  unnecessary. 

The  tendency  of  each  pair  of  leveling-screws  placed  between 
the  parallel  leveling-plates  is  to  produce  opposing  forces,  with 
the  result  that  there  is  an  expansion  of  the  weakest  part  of  the 
metal  forming  the  small  diameter  of  the  screws;  and  conse- 
quently a  corresponding  displacement  of  the  spirit-bubbles  and 
of  other  parts  of  the  instrument  ensues.  Besides,  a  locking  of 
the  screws  sometimes  takes  place;  and  the  retouching  of  the 
screws  for  any  small  displacement,  as  well  as  the  original  level- 
ing-up, requires  the  use  of  both  hands. 

The  present  practice  in  England,  and  through  a  large  part 
of  South  America,  Australia,  etc.,  requires  a  long  equilateral 
triangular  framed  base,  with  three  large  leveling-screws  at- 
tached to  the  theodolite ;  and  this  arrangement  is  very  effective, 

*  Page  98.  t  Page  100. 

15 


212 


REMARKS    ON    MINE-SURVEYING   INSTRUMENTS. 


and  a  complete  remedy  for  all  such  defects  and  inconveniences 
as  are  experienced  from  the  old-fashioned  form  of  four  level- 
ing-screws  and  parallel  leveling-plates.  With  three  leveling- 
screws  there  is  no  opposite  pulling  effect,  because  each  screw 
is  independent  in  its  action  of  the  others ;  and  for  correcting 
any  displacement  of  the  spirit-bubbles  the  use  of  one  hand 
only  is  required. 

Troughton  $>  Simms'  Shifting  Tripod-Head. — Figs.  137, 138  and 
139»  exhibit  separate  parts  of  the  triangular  centering-appa- 
ratus— three  horizontal  plates,  all  turned  upside  down,  as  if  the 
tripod  had  been  completely  overturned,  with  its  feet  pointing 
to  the  sky,  and  with  the  plates  fallen  apart  downwards  in  regu- 
lar order.  Fig.  140,  copied  from  Troughton  &  Simms'  Cata- 
logue of  1900,  shows  the  whole  apparatus  right  side  up,  as  in 

FIG.  137. 


Shifting  Tripod-Head,  Bottom-Plate,  Inverted. 

use.  The  plate  of  Fig.  137  has  a  narrow  slit  about  an  inch 
long  through  it  near  each  end ;  and  a  short,  shouldered  metal 
pin  moves  freely  in  each  slit,  and  likewise  fits  into  and  moves 
freely  in  a  corresponding  slit  near  each  end  of  the  plate  of  Fig. 
138,  that,  in  use,  rests  upon  the  plate  of  Fig.  137.  The  slits 
of  Fig.  138  are  cut  at  right  angles  to  those  of  Fig.  137;  con- 
sequently the  plate  of  Fig.  138  moves  freely  in  two  directions, 
at  right  angles  one  to  the  other,  while  both  plates  are  held  to- 
gether by  the  shouldered  metal  pins.  The  large  hole  in  the 
center  of  the  plate  of  Fig.  137  has  a  female  screw  inside  of  it, 
and  screws  fast  upon  a  corresponding  male  screw  on  the  top  of 
the  tripod-stand  head.  To  the  upper  side  of  the  plate  a  hollow 
thin  cylinder  is  cast,  projecting  upwards,  with  a  male  screw  cut 
upon  it.  This  projecting  male  screw  passes  through  the  large 


REMARKS    ON    MINE-SURVEYING    INSTRUMENTS. 


213 


central  hole  in  the  plate  of  Fig.  138  above;  and  is  worked  upon 
by  the  female  screw  inside  the  central  hole  of  the  circular 
clamp-plate,  Fig.  139,  which  clamps  the  other  two  plates  to- 
gether. The  plate  of  Fig.  139  has  three  small  circular  projec- 
tions upwards  (as  shown  in  the  figure,  downwards),  equidistant 

FIG.  138. 


Shifting  Tripod-Head,  Shifting-Plate,  Inverted. 

one  from  the  other  (seen  also  in  Fig.  140),  forming  an  equilateral 
triangle,  to  which  the  thumb  and  fingers  are  applied  when  it 
is  necessary  to  clamp  and  unclamp  the  plate.  When  the  appa- 
ratus is  put  together  for  use,  right  side  up,  as  in  Fig.  140,  the 
three  conical-shouldered  leveling-screws  of  the  theodolite  are 

FIG.  139. 


Shifting  Tripod-Head,  Clamping-Plate,  Inverted. 

placed  in  angular  cavities  in  the  upper  surface  of  the  triangular 
projecting  ends  of  Fig.  138,  and  are  then  locked  in  that  position 
by  another  thin  plate,  which  has  a  slight  horizontal  motion, 
and  is  thereby  secured  in.  a  groove  by  a  conical  head  turned  in 
the  shank  of  the  leveling-screws.  Part  of  this  thin  plate  is 


214 


REMARKS    ON    MINE-SURVEYING   INSTRUMENTS. 


FIG.  140. 


seen  projecting  from  under  the  (inverted)  plate  of  Fig.  138, 
and  it  is  clamped  in  position  by  the  milled-headed  screw  also 
seen  in  Fig.  138.  The  construction  and  use  of  this  simple, 
light  and  effective  apparatus  are  well  known.  It  is  the  inven- 
tion of  Troughton  &  Simms,  and  is  supplied  with  all  their  in- 
struments. 

When  the  theodolite  is  locked  in  position  upon  this  leveling 
and  centering  apparatus,  and  it  is  required  to  center  it  over  a 
fine  point  marking  a  survey  station,  it  is  first  done  roughly  by 
moving  the  legs  of  the  tripod-stand,  leveling  up ;  and  then  the 
clamp-plate,  Fig.  139,  is  unscrewed  a  little,  leaving  the  theod- 
olite and  upper  part  of  the  leveling 
and   centering   apparatus,   Fig.   138, 
free   to  move   in  two    directions,   at 
right  angles  one  to  another,  upon  the 
plate  of  Fig.  137,  which  is  fixed  upon 
the  tripod-stand,  until  the  fine  point 
of  the  plumb-bob  coincides  with  the 
center  of  the    survey  station.      The 
circular  clamp-plate,  Fig.  139,  is  then 
screwed    down   tight,  fixing   the  in- 
strument in  position  for   immediate 
use.     The  whole  of  these  operations 
may  be    effected   almost   instantane- 
ously. 

It  is  very  important  to  possess  some 
such  means  as  those  described  to  en- 
able the  engineer  to  center  the  the- 
odolite over  a  survey  station-mark  with  great  precision  and 
rapidity,  because  a  greater  geometrical  approximation  to  the 
truth  may  be  obtained.  To  do  this  perfectly  by  simply  moving 
the  tripod  legs  is  difficult  and  almost  impossible;  and  the 
attempt  is  the  fertile  source  of  a  small  repeated  accumulating 
error,  the  total  amount  of  which  in  an  extensive  survey  cannot 
§  be  estimated  or  determined  until  an  irregular  polygon  has 
been  described.  The  facilities  for  such  control  in  underground 
surveys  do  not  often  exist. 

Hoskold's  Shifting  Tripod-Head. — The  top  part  of  a  theodo- 
lite-stand invented  by  the  writer  in  1866  consisted  of  a  circular 
metallic  box,  to  the  underside  of  which  the  legs  were  attached ; 


Shifting  Tripod-Head,  Com- 
plete, Upright. 


REMARKS    ON    MINE-SURVEYING    INSTRUMENTS.  215 

and  in  the  middle  of  the  upper  part  a  strong  circular  plate  was 
fitted,  having  a  circular  motion  of  about  one  inch  in  all  direc- 
tions horizontally.  At  the  center  of  the  plate  a  large  hollow 
screw  was  cast,  projecting  upwards  to  a  height  of  about  1} 
inches,  upon  which  the  theodolite  was  screwed ;  but  not  close 
down,  until,  by  moving  the  theodolite  and  plate  about,  the 
plumb-bob  was  centered  over  the  station.  The  instrument  was 
then  screwed  down  ready  for  use. 

Hoskold's  Extensible  Tripod.— That  theodolite-stand  of  1866 
was  planned  for  underground  use,  and  each  leg  consisted  of 
three  tubes  sliding  one  into  another.  On  the  outside  termina- 
tion of  each  tube  a  screw  was  cut,  and  the  ends  of  the  tubes 
were,  at  two  places  in  each,  slit  up  two  inches  in  length  by  saw 
cuts,  in  order  to  compress  the  outer  tubes  against  the  inner 
ones  when  a  stout  outside  collar  screw  was  brought  into  action 
at  each  joint.  In  that  manner  the  tubes  were  effectually 
clamped  together.  The  stand  could  be  set  up  from  18  inches 
to  about  4  feet  in  height.  But  after  some  time  the  sliding  of 
the  tubes  and  the  action  of  the  collar-screw  clamps  were  much 
impeded  by  water  and  dirt.  Besides,  the  stand  was  too  heavy. 
All  of  those  inconveniences  caused  it  to  be  abandoned.  It 
may,  however,  be  possible  to  construct  a  stand  of  this  type  in 
aluminum  metal  alloyed,  so  as  to  be  of  service.  Nevertheless, 
three  short  stands  of  a  special  construction  would  be  prefera- 
ble. Part  of  the  construction  of  the  tubular  stand  noted  was 
similar  to  that  of  Mr.  Stanley's,  referred  to  by  Mr.  Scott.* 

Electric  Lamp. — The  small  portable  electric  lamp  mentioned 
by  Mr.  Scott  is  exceedingly  convenient  and  useful,  setting  aside 
the  use  of  candle  lights  and  oil  lamps,  and  facilitating  in  a  high 
degree  the  reading  of  theodolite  verniers  underground.  A 
diagram  or  graphic  representation  of  it  when  in  use  in  mine- 
surveys  should  have  been  introduced  in  Mr.  Scott's  discussion. 
Probably  he  will  favor  us  with  it  on  some  future  occasion. 
Fig.  84 1  shows  to  what  extent  inventions  have  been  applied  in 
order  to  achieve  a  similar  purpose ;  but  it  is  a  cumbrous  mode, 
and  cannot  be  compared  to  the  efficient  little  lamp  described 
by  Mr.  Scott. 

Plumb-Lines. — Mr.  Hulbert  is  right  in  saying  :J 

*  Pages  46,  47.  f  Page  127.  J  Page  149. 


216  REMARKS    ON    MINE-SURVEYING    INSTRUMENTS. 

' '  I  should  place  more  reliance  upon  a  downward  sight  through  a  properly  con- 
structed and  accurately  adjusted  telescope  than  in  the  repose  of  a  plumb-line. 
We  trust  the  telescope  for  the  measurement  of  all  horizontal  distances,  and  we 
never  question  its  accuracy  in  taking  inclined  angles  and  observations ;  now, 
therefore,  why  not  accord  it  the  same  confidence  in  taking  a  truly  vertical  sight? 
Except  for  moderately  short  distances,  I  always  considered  the  plumb-line  a 
positive  nuisance,  a  consumer  of  time  and  a  disagreeable  tester  of  patience." 

He  could  also  have  added :  without  any  positive  certainty, 
for  either  long  or  short  distances.  It  is  nevertheless  to  he 
feared  that  persons  will  always  exist  capable  of  trying  every 
obsolete  fad. 

Chain. — A  steel  standard  chain  is  an  expeditious  measuring- 
instrument  for  underground  work,  and  excellent  results  may  be 
obtained  by  its  use ;  at  the  same  time,  it  is  well  to  carry  a 
pocketrrule  divided  to  tenths  of  inches,  for  measuring  any  odd 
part  of  a  link  which  may  coincide  with  a  station.  Any  tunnel 
or  other  important  drivage  from  two  opposite  points,  or  other- 
wise, depending  upon  the  survey,  may  then  be  carried  out  with 
confidence.  For  still  more  accurate  work,  another  class  of 
linear  measuring  instrument  could  be  devised  similar  to  those 
employed  to  measure  base-lines  in  trigonometrical  surveys, 
though  simpler ;  but  it  would  only  be  used  on  rare  occasions. 

II. — INSTRUMENTS. 

Compass. 

Mine  Compass  of  1518. — Figs.  141  and  142  are  two  forms 
of  mine-surveying  compasses  taken  from  the  old  rare  German 
mining  book,  Eyn  woldgeordent  und  nutzlich  buchlin  wie  man  Berg- 
werck  suchen  un  finden  sol.  Edition  1518.  This  work  with 
three  other  editions,  namely,  1527,  1534  and  1539,  are  pre- 
served in  the  Royal  Mining  Academy  at  Freiberg  in  Saxony. 
The  1504  edition  of  that  book,  the  rarest  of  all,  does  not  exist 
there.  The  compasses  for  mine-surveying — if  they  were  so 
used — represented  by  Figs.  141  and  142  differ  somewhat  in 
form  and  size  in  all  the  editions  of  the  book  referred  to.  For 
example,  Fig.  141,  which  appears  to  be  the  oldest,  is  divided 
into  twice  12  hours,  and  has  a  small  circle  inscribed  round  the 
central  point,  upon  which  probably  a  small  magnetic  needle 
was  placed.  Fig.  142  has  two  concentric  circles,  each  divided 
into  twice  12  hours,  one  end  of  the  magnetic  needle  being 
forked. 


REMARKS    ON    MINE-SURVEYING    INSTRUMENTS. 


217 


Compass  of  1541  and  Agricola' s  of  1556. — Mr.  Brough,  in 
discussing  Mr.  Scott's  paper,  said:* 

"  The  author  is  inaccurate  in  stating  that  the  use  of  the  compass  in  mine-sur- 
veys is  first  described  by  Agricola." 

It  is,  however,  curious  that  Mr.  Brough  has  conveyed  the 
same  sense  and  employed  nearly  the  same  words  in  his  little 
book  on  Mine-Surveying  from  1888  to  1899.  At  page  26  he  says  : 


FIG 


Earlier  Mine-Surveying  Compass  of  1518. 

"  The  use  of  the  magnetic  needle  for  surveying  mines  is  first  described  by 
Georgius  Agricola,  in  the  fifth  book  of  his  De  Re  Metallic^  1556. 

"  The  compass  there  described  is  of  a  very  primitive  character An  old 

compass  of  this  type  is  preserved  in  the  collection  of  the  School  of  Mines  of 
Clausthal,  in  the  Harz.  It  bears  date  1541." 

The  comparatively  limited  space  of  only  three  circular  con- 
centric grooves  filled  with  wax,  upon  which  to  indicate  the 
direction  of  underground  roads,  is,  in  the  writer's  opinion, 
enough  to  prove  that  the  Clausthal  compass  is  an  older  form 
than  Agricola's.  The  latter  was  provided  with  seven  circular 
concentric  grooves  filled  with  wax,  and  was  consequently  capa- 

*  Page  68. 


218 


REMARKS    ON    MINE-SURVEYING    INSTRUMENTS. 


ble  of  being  employed  in  more  extended  surveys,  such  as  a  pro- 
gressive system  of  mining  operations  required.  ~No  doubt  the 
mine-surveying  compass  of  1541  and  Agricola's  of  1556  are  im- 
provements upon  the  older  forms,  Figs.  141  and  142,  of  1504 
and  1518 ;  for  in  these  it  would  appear  that  anything  finer  than 
an  entire  division  of  one  hour  had  to  be  estimated  by  some 
other  means.  On  the  contrary,  the  actual  direction  of  any  un- 

FIG.  142. 


Later  Mine- Surveying  Compass  of  1518. 

9 

derground  road  was  indicated  by  a  scratched  line  on  the  wax 
of  the  Setz-compass  and  Agricola's  compass. 

VoigteVs  Setz-Compass. — Mr.  Scott  has  referred*  to  a  very 
curious  form  of  mine-surveying  instrument,  the  astrolabe,  a 
simple  plane  circle  supported  in  a  horizontal  position,  illus- 
trated in  an  excellent  old  German  book;f  but  he  has  omitted 
to  note  the  Setz-compass  of  the  same  work,  although  it  is 
equally  interesting.  J  It  has  the  same  form  as  the  survey  ing- 


*  Page  120. 
t  Ibid.,  p.  72. 


t  Voigtel's  Geometria  Subterranea,  p.  146,  1686. 


REMARKS    ON    MINE-SURVEYING    INSTRUMENTS.  219 

compass  of  Fig.  141,  date  1518.  It  seems,  therefore,  probable 
that  that  class  of  instrument  may  have  been  used  for  a  period 
of  two  centuries,  or  more.  The  words  midnight,  midday  and 
other  names  corresponding  to  certain  defined  points,  engraved 
outside  and  around  the  circle  or  compass,  indicate  that  it  may 
have  been  a  copy  or  a  modification  of  some  other  more  ancient 
instrument,  say  an  astrolabe  employed  for  some  other  class  of 
observations,  such  as  a  rough  estimation  of  time  and  general 
direction.  A  very  curious  group  of  ancient  mathematical  in- 
struments forms  part  of  the  artistically  engraved  frontispiece  of 
the  same  book,  and  would  be  worth  reproducing. 

Circumferentor. — The  circumferentor  described  by  Bion  is 
nearly  the  same  as  the  miner's  dial-circumferentor  with  plain 
sights  as  constructed  to-day,  but  is  a  little  ruder  in  form  than 
Fig.  12*  in  Mr.  Scott's  paper.  It  appears  that  Pryce  did  not 
know  anything  about  this  old  dial  in  1778. 

Stanley's  Hedley  Dial. — Mr.  Stanley  recently  introduced,  as  he 
says,  a  new  form  of  Hedley  dial,  patented,  Fig.  63.  f  It  is  con- 
structed with  an  oval-shaped  curved  cradle  carrying  the  telescope, 
and  having  a  vertical  circle  attached,  instead  of  with  a  ring  and 
semicircle,  as  in  the  old  type  dials,  Figs.  25  and  40. J  The 
principal  advantage  to  be  derived  from  a  vertical  circle  is  that 
it  offers  means  for  obtaining  two  readings,  one  opposite  the 
other ;  but  Mr.  Stanley  has  not  availed  himself  of  this  estab- 
lished principle,  making  the  circle,  therefore,  no  more  important 
than  a  semicircle.  In  this  age  of  unprecedented  progress,  fa- 
cility and  accuracy  of  working,  no  practical  person  should  pre- 
fer the  old-fashioned  and  coarse  method  of  engraved  correc- 
tions "  in  hypothenuse  and  base  "  upon  an  instrument,  when 
the  same  thing  in  an  accurate  form  is  included  in  a  table  of 
natural  sines  and  cosines. 

Mr.  Stanley  says  :  "  It  is  the  first  dial  of  the  Hedley  style,  I 
believe,  which  may  be  used  for  sighting  in  true  verticality." 
But  he  has  provided  no  means  to  adjust  the  horizontal  axis 
upon  which  the  cradle  and  telescope  work;  at  least,  such  an 
adjustment  is  not  described,  nor  does  it  appear  in  Fig.  63.  Con- 
sequently, there  is  no  certainty  that  the  vertical  hair  of  the  tele- 
scope would  under  all  conditions  revolve  permanently  in  the 

*  Page  14.  f  Page  75.  J  Pages  31  and  45. 


220  REMARKS    ON    MINE-SURVEYING    INSTRUMENTS. 

same  vertical  plane.  Considering  this  and  the  comparatively 
rough  construction  always  inherent  in  this  class  of  instrument, 
the  writer  is  of  opinion  that  it  would  not  be  a  convenient  or 
absolutely  trustworthy  instrument  for  carrying  out  that  very 
delicate  and  important  operation  of  connecting  underground 
workings  one  to  another  and  to  the  surface,  for  the  purpose  of 
executing  some  important  and  costly  work.  If,  however,  the 
contrary  held  good,  the  telescope  is  not  conveniently  constructed 
for  facile  work ;  neither  is  it  sufficiently  powerful  except  for 
comparatively  short  distances  down  pits  or  severe  inclines,  or 
for  surveys  of  no  great  importance.  The  instruments  of  both 
Figs.  40  and  63  and  all  others  of  that  type  are  comparatively 
cumbrous,  rough  in  construction,  and  neither  the  one  nor  the 
other  can  ever  be  made  to  approach  the  nice  and  beautiful  con- 
struction of  a  well-proportioned  and  high-class  theodolite. 
Doubtless,  however,  many  persons  will  employ  the  one  of  Fig. 
63  for  second-rate  underground  surveys  in  which  great  accuracy 
is  not  considered  a  sine  qua  won. 

If  Mr.  Stanley  desires  to  improve  his  instrument,  and  so  ren- 
der it  of  greater  value  for  mine-surveying,  it  would  be  well  to 
provide  an  adjustment  to  the  horizontal  axis,  supply  an  axis 
level  and  means  to  illuminate  the  cross-hairs  in  the  focus  of  the 
telescope.  The  best  means  of  doing  this  is  exhibited  in  Figs. 
76  and  77.*  An  oblong  hole  is  cut  in  the  side  of  the  telescope 
near  its  eye  end  and  filled  with  glass,  with  a  slide  for  protection. 
A  reflector  may  be  placed  inside  to  throw  the  light  upon  the 
wires.  If  a  magnetic  bearing  is  of  any  value,  the  instrument  of 
Fig.  63  would  preferably  have  a  more  open  dial  face ;  for,  in  its 
present  form,  it  would  be  difficult  to  obtain  a  clear  view  all 
round  the  circle,  even  when  the  cradle  and  telescope  are  tilted 
to  the  perpendicular.  If  the  magnetic  compass  should  be  re- 
quired at  all,  it  would  be  best  mounted  on  the  top  of  the  tele- 
scope, as  is  the  case  in  the  writer's  Engineer's  Theodolite,  Fig. 
76.t 

Compass  on  Telescope. — The  sliding  magnetic  compass  was 
attached  to  the  telescope  of  the  theodolite,  Fig.  17,|  many  years 
since  by  the  writer;  and  the  same  plan  has  been  continued  for 
his  Engineer's  Theodolite,  Fig.  75. § 


Pages  105  and  106.      f  Page  105.      t  Page  20.  •    §  Page  100. 


REMARKS    ON    MINE-SURVEYING   INSTRUMENTS.  221 

Hanging  Compass. — Referring  to  the  remarks  of  Mr.  Johnson* 
upon  Mr.  Scott's  opinion  as  to  the  magnetic  hanging  compass 
in  mine-surveying,  the  writer  agrees  with  Mr.  Johnson  in  a 
limited  sense.  That  is,  when  the  purpose  of  the  survey  is 
merely  to  obtain  a  rough  diagram  of  the  workings  in  a  mine, 
the  general  direction  of  any  mineral  vein,  and  a  variety  of 
other  things,  without  aiming  at  an  exact  map  or  plan  of  such 
underground  objects  with  relation  to  the  surface,  to  boundary 
lines,  to  the  formation  of  a  tunnel  from  two  opposite  points,  or 
to  striking  any  given  bore  hole,  and  to  other  important  matters ; 
then,  any  handy  inexpensive  magnetic  compass  may  be  em- 
ployed, and  time,  inconvenience  and  money  saved.  It  is  evi- 
dent, therefore,  that  a  finely  divided  theodolite  should  not  be 
taken  into  every  hole  and  corner  of  a  mine.  However,  when 
all  the  conditions  just  indicated  are  reversed,  then  such  instru- 
ments as  would  enable  the  surveyor  to  produce  the  most  accu- 
rate results  should  be  employed,  and  the  amount  of  time  and 
expense  necessary  to  effect  this  should  not  be  considered. 

Lack  of  Precision. — It  is  strange  that  some  men  continue  to 
urge  that  the  use  of  the  magnetic  compass  is  sufficient  for  un- 
derground surveys,  and  it  is  difficult  to  assign  a  reason ;  though 
we  may  assume  that  facility  and  simplicity  of  use,  hereditary 
custom  and  the  comparatively  small  cost  of  such  instruments 
are  some  of  the  chief  reasons  why  the  miner's  compass  is  still 
clung  to  in  some  form  or  another  so  tenaciously.  But  in  the 
face  of  a  well-known  law  of  Newton  are  we  to  ignore  the  re- 
sults of  the  modern  solution  of  some  of  the  most  curious,  dif- 
ficult and  important  natural  physical  problems  ? 

The  scientific  men  of  to-day  have  proved  that  even  the 
highest  class  surveys,  which  have  been  conducted  upon  the 
most  refined  and  rigid  mathematical  principles,  are  affected  in 
a  variable  degree  through  the  deflection  of  the  plumb-line  by 
close  neighboring  mountain  masses  and  rocks  of  the  greatest 
density.  One  of  the  most  interesting  and  important  records 
we  possess  is  that  which  relates  to  the  setting  out  of  the  bound- 
ary-line between  the  territory  of  the  United  States  and  the 
possessions  of  Great  Britain  between  the  Lake  of  the  Woods 
and  the  Rocky  Mountains.  The  part  of  the  report  of  the  chief 

*  Page  129. 


222  REMARKS    ON    MINE-SURVEYING   INSTRUMENTS. 

astronomer  and  member  of  the  mixed  commission  that  relates 
to  the  deviation  of  the  boundary-line,  as  set  out,  from  the  true 
astronomical  parallel  of  latitude,  is  applicable  to  the  question 
to  which  the  writer  desires  to  direct  attention.  He  says:* 

"The  fact  of  local  deflection  being  established,  the  attention  of  mathema- 
ticians was  turned  to  the  investigation  of  the  causes  and  probable  corrections. 
In  this  much  ingenuity  has  been  displayed,  but  with  very  small  results.  Starting 
with  the  general  law  [of  Newton],  that  every  particle  of  matter  attracts  each  other 
particle  with  a  force  varying  directly  with  the  mass  and  inversely  with  the  square 
of  the  distance,  the  attraction  of  masses  of  mathematical  forms  on  distant  parti- 
cles was  found  by  dividing  mountain-ranges  and  other  elevations  into  volumes 
bearing  known  mathematical  relations.  The  probable  deflection  of  the  plumb- 
line  due  to  such  causes  was  found  for  different  distances,  on  the  supposition  that 
the  mean  density  of  the  large  volumes  was  uniform  for  different  parts  of  the 
earth's  crust  [ — a  thing  quite  impossible].  Thus,  it  was  found  that  at  the  northern 
station  of  the  great  Indian  arc  the  attraction  of  the  Himalayas  should  cause  a 
deflection  of  28" ;  which  should  decrease  at  the  next  two  principal  stations  by 
15".  9  and  21".  1,  respectively,  while  the  deficiency  of  matter  in  the  ocean  should 
produce  similar  northern  deflections.  These  calculations  were  not  absolute,  since 
the  contour  of  the  mountains  and  of  the  ocean-bed  was  only  approximately 
known ;  but  the  approximations  were  supposed  to  be  sufficiently  close.  It  was 
found,  however,  that  the  actual  deflections  were  much  smaller  than  those  given 
by  calculation  ;  and  that,  in  many  cases,  the  deflection  was  towards  the  ocean. 
The  explanation  of  this  lies  in  the  varying  density  of  the  earth's  crust.  The 
facts  discovered  indicate  that  the  density  is  greatest  in  the  depressed,  and  less  in 
the  elevated  portions." 

From  the  doctrine  here  laid  down,  upon  Newton's  law,  we 
must  conclude  that  the  maximum  density  and  effect  occurs 
from  the  presence  of  intrusive  dikes  which  have  penetrated 
the  earth's  crust  to  a  great  extent;  and,  although  some  of  those 
dikes  are  not  visible,  still  the  denser  masses  of  such  intrusions 
produce  very  great  effect.  As  every  one  knows,  the  magnetic 
needle  consists  of  a  light  bar  of  steel  suspended  freely  upon  a 
fine  central  point,  and  in  a  horizontal  position.  Consequently 
it  is  liable  to  be  acted  upon  and  deflected  an  unknown  quantity 
by  the  greater  and  denser  masses  of  rocks  which  form  intrusive 
dikes.  This  effect  may  exist,  although  not  suspected;  but 
whatever  its  amount  may  be,  it  is  independent  of  the  de- 
flection of  the  needle  caused  by  ferruginous  masses  and  the 

*  Reports  upon  the  Survey  of  the  Boundary  between  the  Territory  of  the  United  States 
and  the  Possessions  of  Great  Britain,  Department  of  State,  Washington,  1878,  p. 
263.  Also  in  Executive  Documents,  Senate  of  United  States,  1877,  No.  41,  p.  26, 
Washington,  1877. 


REMARKS    ON    MINE-SURVEYING    INSTRUMENTS.  223 

other  common  deviations  to  which  the  magnetic  needle  is  sub- 
jected. 

The  writer  is  nevertheless  aware  that  magnetic  surveys  are 
sometimes  conducted  in  places  more  or  less  free  from  natural 
disturbances;  and,  in  such  a  case,  when  great  care  has  been 
taken  in  manipulating  the  instrument,  and  when  there  has  been 
a  large  share  of  good  luck,  close  approximation  to  the  truth 
has  resulted.  But  such  favorable  conditions  cannot  always  be 
expected  to  be  realized.  It  would  therefore  be  dangerous  to 
place  too  much  reliance  upon  the  accurate  performance  of  the 
magnetic  needle  on  all  occasions  and  under  varying  circum- 
stances. The  history  of  mine-surveying  proves  that  some  per- 
sons have  placed  absolute  reliance  upon  the  magnetic  needle, 
and  have  come  to  grief.  The  erratic  behavior  of  the  mag- 
netic needle,  and  consequently  the  uncertainty  of  the  observa- 
tions made  with  it,  as  just  indicated,  are  confirmed  by  Mr.  Hul- 
bert* ;  and  in  addition  to  the  list  of  disturbing  elements  pre- 
viously noted,  he  has  noted  another,  namely,  "  electric  currents 
following  either  wall  of  a  vein  "  of  mineral. 

Plane- Table. 

Referring  to  Mr.  Scott's  discussion,  a  plane-table  similar  to 
that  described  under  Fig.  62 f  was  in  use  in  England  and 
France  more  than  120  years  earlier.  An  old  English  work 
translated  from  the  FrenchJ  says,  in  substance,  somewhat  con- 
densed : 

"The  plain-table  is  a  parallelogram  of  wood,  15  inches  long  and  12  broad," 
having  "  a  box-frame  to  fasten  a  sheet  of  paper  upon  the  table,  by  forcing  down  the 
frame  and  squeezing  in  the  edges  of  the  paper,  so  that  it  lies  firm  and  even  upon 
the  table ;  and  thereby  the  plot  of  a  field,  or  other  enclosure,  may  conveniently 
be  drawn  upon  it.  On  both  sides  of  this  frame,  near  the  inward  edge,  are  scales 
of  inches  subdivided  into  10  equal  parts,  having  their  proper  figures  set  to  them. 
The  use  of  these  scales  is  for  ready  drawing  of  parallel  lines  upon  the  paper,  and 
also  for  shifting  the  paper  when  the  sheet  will  not  hold  the  whole  work.  Upon 
one  side  of  the  box-frame  are  projected  360  degrees  of  a  circle,  from  a  brass  center 
hole  in  the  middle  of  the  table.  Each  degree  is  subdivided  into  30  minutes,  and 
to  every  10th  degree  are  set  two  numbers,  one  expressing  the  proper  number  of 
degrees,  and  the  other  the  complement  of  that  number  of  degrees  to  360.  This 
is  done  to  avoid  the  trouble  of  subtraction  in  taking  angles.  On  the  other  side 

*  Page  147.  f  Page  74. 

J  Stone's  Bion,  Construction  of  Mathematical  Instruments,  p.  127  and  Fig.  F,  plate 
xiii.,  London,  1723. 


224  REMARKS    ON    MINE-SURVEYING   INSTRUMENTS. 

of  the  frame  and  upon  a  part  of  its  width  are  projected  the  180  degrees  of  a  semi- 
circle from  a  brass  centre  hole  in  the  middle  of  the  table's  length.  Each  degree 
is  subdivided  to  30  minutes  ;  to  every  10th  degree  are  set  likewise,  as  on  the  other 
side,  two  numbers ;  one  expressing  the  proper  number  of  degrees,  and  the  other 

the  complement  of  that  number  of  degrees  to  180 All  these  degrees  will 

make  the  plain-table  a  theodolite  or  a  semicircle,  according  to  what  side  of  the 
frame  is  uppermost.  There  is  a  box  with  a  needle  and  card,  covered  with  a  glass, 
fixed  to  one  of  the  long  sides  of  the  table.  There  is  also  belonging  to  the  table 
an  index,  which  is  a  large  brass  ruler,  at  least  16  inches  long  and  2  inches  broad, 
and  so  thick  as  to  make  it  strong  and  firm,  having  a  sloped  edge,  and  two  sights 
screwed  perpendicularly  on  it.  Upon  this  index  it  is  usual  to  have  many  scales  of 
equal  parts  ;  as  also  diagonals  and  lines  of  chords,"  etc. 

From  this  and  the  description  given  by  Mr.  Scott,*  there 
appears  to  have  been  no  improvement  in  plane-tables  from 
1657f  t°  1834,  when  Simms  wrote. 

Octant  and  Quadrant. 

In  an  old  Latin  book  on  surveying  and  astronomical  instru- 
ments, J  an  instrument  called  an  octant — the  eighth  part  of  a 
circle — is  exhibited,  together  with  various  diagrams  illustrative 
of  its  application.  That  work  contains  evidence  that  the  in- 
strument referred  to  was  used  prior  to  1604,  and  at  least  up  to 
1612.  Fig.  143  is  a  reduction  of  the  original  diagram  of  the 
octant,  the  length,  or  radius,  of  which  was  15  inches.  The 
limb  has  5  concentric  arcs  engraved  upon  it,  and  it  is  a  good 
example  of  subdividing  the  degrees  into  parts  by  diagonal  lines. 
The  distance  from  the  first  divided  arc  to  the  exterior  one  is 
1 J  inches,  and  the  diagonal  lines  are  drawn  from  the  whole  de- 
gree points  on  the  first  arc  to  the  half  degree  points  on  the  ex- 
terior arc.  The  diagonal  lines  are,  moreover,  divided  by  fine 
dots,  so  as  to  read  to  every  two  minutes.  Fig.  144  shows  two 
such  instruments  set  up,  with  four  observers  determining  a 
distance. 

A  quadrant  without  subdivisions  by  diagonal  lines  was  used 
in  England  for  surveying  operations  by  Delamain  in  1632.  § 
Circles  were,  however,  employed  before  1529  in  Spain  and 

*  Page  74. 

f  The  Complete  Surveyor,  Containing  the  Whole  Art  of  Surveying  of  Land  by  the  Plane- 
Table^  Theodolite,  Circumferentor,  etc.  Second  edition,  W.  .Lebourn,  1657. 

J  De  Octantis  Instrument  Mathematici  Novi  Geodcetis,  Astronomis,  Nautis  Usu,  etc. 
Henrico  Hofmanne,  Jena,  1612. 

f  A  Mixed  Trapezium  or  Horizontal  Quadrant  for  Mathematical  Practice,  Delamain, 
1632. 


REMARKS    ON    MINE-SURVEYING    INSTRUMENTS. 


225 


other  places.  It  is,  therefore,  somewhat  strange  that  the  use 
of  octants  and  quadrants  should  have  been  continued  in 
preference. 


FIG.  143. 


^>      ^  \   **8E^&XC*£lk 

---J        A    *-  _     Orfe«A..Mrjr  A*  jxnur  -__??/  f>       .' 


^^is^^ 

^T^^^/C"  ?/:  -^^raS— fT" 
7"/  r/--  j  tTTr-^h  r-r^-T-T-r-M--rr 


•*\ 


Octant. 

Theodolite  and  Transit. 

Evolution  of  the  Theodolite. — The  German  instrument  of  Fig. 
145  is  illustrated  in  a  curious  black-letter  book  of  38  pages  on 
surveying;*  and,  at  the  time,  was  considered  to  be  of  great 


*  Instrument  zur  Mechanica,  A.  Albrecht,  1673. 


226 


REMARKS    ON    MINE-SURVEYING    INSTRUMENTS. 


importance.  It  is  possible  that  it  was  employed  in  mine-sur- 
veying. In  the  original  description,  A  is  a  small  compass-box, 
containing  a  magnetic  needle,  with  the  four  cardinal  points 
marked.  B  shows  an  indicator  to  which  the  compass-box  is 
screwed,  both  of  which  revolve  horizontally.  C  is  a  fixed 
graduated  circle  placed  under  the  indicator  B,  and  is  divided 

FIG.  144. 


Octant  in  Use. 

into  360° ;  also  the  four  cardinal  lines  are  marked  upon  it.  D 
is  a  circular  writing-table  placed  under  the  divided  circle  and 
extending  concentrically  beyond  it.  E  is  a  bound  book,  part 
of  the  instrument,  to  which  all  the  other  parts,  previously  de- 
scribed, are  firmly  attached.  The  book  was  intended  for  writ- 
ing and  drawing.  FG  represents  a  tube  or  telescope,  attached 
by  means  of  a  short  axis  and  appendage  to  the  side  of  the  book. 


REMARKS    ON    MINE-SURVEYING   INSTRUMENTS. 


227 


A  vertical  semicircle  was  also  fixed  to  the  underside  of  the  tele- 
scope, and  the  vertical  angles  were  indicated  by  swinging 
pendulums  suspended  from  the  short  horizontal  axis  previously 
noted.  NQP  represents  the  upper  part  of  the  stand,  with  joints 
for  giving  horizontal  motion  to  the  instrument.  The  cylindri- 
cal part  at  !N"  appears  to  have  been  divided.  When  in  use,  the 
telescope  of  this  instrument  was  directed  to  an  object  and  the 
index  bar,  B,  was  then  moved  by  hand  round  the  divided  circle, 


FIG.  145. 

INSTRUMENT* 


Albrecht's  Instrument. 

until  the  magnetic  needle  pointed  north  and  south ;  and  the 
bearing  angle  of  the  observed  object  was  then  obtained  from 
the  divided  circle. 

The  instrument*  shown  in  Fig.  106f  seems  to  be  an  im- 
proved form  and  probably  derived  from  that  of  Fig.  145.  In 
an  old  English  book,J  translated  from  the  French,  a  graph- 
ometer,  or  surveying  horizontal  semicircle,  is  represented  with 

*  Geometria  Forensis,  Keinhold,  1781,  p.  106  and  plate  xii.  f  Page  168. 

J  Stone's  translation  of  Bion,  on  Mathematical  Instruments,  p.  121,  1723. 

16 


228  REMARKS    ON    MINE-SURVEYING    INSTRUMENTS. 

double  sights,  the  one  fixed  and  the  other  movable,  as  in  the 
instrument  of  Fig.  106,  but  without  vertical  motion  for  either 
of  the  sights.  The  upper  telescope  of  Fig.  106,  however,  has 
a  vertical  motion,  proving  that  it  is  of  more  recent  construc- 
tion, and  approaching  towards  the  simplest  form  of  theodolite. 
The  idea  of  attaching  a  vertical  arc  to  the  telescope  of  the  in- 
strument of  1781,  Fig.  106,  seems  to  have  been  derived  from 
the  large  geodetic  altazimuth  of  Ramsden,  which  at  that  time 
was  so  well  known  throughout  Europe.  Semicircles  with  plain 
sights  were,  however,  mounted  upon  the  diameter  of  horizontal 
circles  about  1766. 

The  great  inventor  Ramsden  completed  his  dividing-engine 
in  1773,  after  ten  years  of  incessant  labor,  and  his  great  36-inch 
diameter  theodolite,  Fig.. 146,  soon  after.  Delambre  styles  him 
a  "  celebrated  English  optician,  the  greatest  of  all  artists,  and 
the  inventor  of  the  theodolite."  To  Ramsden  is  attributed  the 
introduction  of  the  vertical  in  combination  with  the  horizontal 
circle  in  the  same  instrument.  Ramsden  constructed  two  36- 
inch  theodolites,  one  for  the  Royal  Society,  and  the  other  for 
the  English  government.  It  is  understood  that  both  the  in- 
struments were  employed  on  the  English  Trigonometrical  Sur- 
vey. One  of  them  is  still  preserved  in  good  working  condition 
in  the  Ordnance  Survey  Offices.  A  notice  of  both  instruments 
will  be  found  in  the  History  of  the  Royal  Sappers  and  Miners.* 
The  horizontal  circle  appears  to  have  been  read  by  four  micro- 
metrical  microscopes  and  to  one  second  of  arc.  The  telescope 
was  used  for  distances  up  to  112  miles. 

Scott's  Tachometer. — The  writer  has  made  no  objection  to  Mr. 
Scott's  "  interchangeable  auxiliary  telescope  when  placed  on  the 
top  of  the  main  telescope  under  conditions  almost  identical  with 
the  others  mentioned. "f  All  that  can  fairly  be  deduced  from 
the  writer's  observations^  is,  that  he  considers  the  models  Fig. 
45  and  Fig.  55  superior  to  all  the  other  preceding  ones  described 
by  Mr.  Scott.  It  was  not  intended  to  include  Figs.  56  and  57 
in  that  list ;  but  between  these  two  a  comparison  was  made  in 
reference  to  the  mode  of  attaching  the  auxiliary  telescope,  with 
its  possible  effects.  However  much  experience  a  man  may  have, 


*  Royal  Engineers,  1857,  vol.  ii.,  p.  408.  t  Page  121. 

J  Page  109. 


REMARKS    ON    MINE-SURVEYING    INSTRUMENTS. 


229 


it  would  be  exceedingly  unwise  to  attempt  to  criticise  in  too  strict 
a  manner  the  merits  or  demerits  of  an  instrument  he  had  not 

FIG.  146. 


Kamsden's  36-Inch  Theodolite. 


seen  or  proved.     Considering,  therefore,  that  Mr.  Scott's  form 
of  instrument  is  a  recent  introduction,  he  naturally  must  be 


230  REMARKS    ON    MINE-SURVEYING   INSTRUMENTS. 

the  best  expert  with  reference  to  its  advantages  and  use,  and 
we  must  consequently  hear  him,  and  give  credit  to  his  evidence. 
It  is,  however,  difficult  to  convince  men  that  the  form  of  in- 
strument they  have  been  accustomed  to  use  is  not  the  best. 
This  is  the  way  and  prejudice  of  the  world,  and  it  is  a  hard 
matter  indeed  to  supplant  entirely  the  old  for  the  new,  although 
the  latter  may  be  vastly  superior. 

HoskotcPs  Engineer's  Theodolite. — Referring  to  Mr.  Scott's  re- 
marks,* the  writer  cannot  find  sufficient  reason  to  change  the 
present  form  of  his  Engineer's  Theodolite,  Fig.  75, f  to  the 
form  of  an  ordinary  transit  theodolite.  The  description  which 
the  writer  has  already  given  of  that  instrument^  was  intended 
to  be  sufficient  to  enable  anyone  to  perceive  the  reason  why  it 
was  constructed  in  its  pr.esent  distinctive  form.  When  the  de- 
sign was  last  under  revision,  it  was  decided  that,  whilst  the  in- 
strument should  be  adapted  for  general  surveying  use,  it  was 
also  imperative  that  it  should  be  kept  as  low  down  in  con- 
struction as  possible,  and  in  as  compact  a  form  as  convenience 
would  permit.  These  conditions  were  necessary,  considering 
that  an  instrument  in  that  form  would  be  better  appreciated 
and  useful  among  the  more  experienced  surveyors  in  collieries 
and  other  mines  and  places  where  severe  angles  of  depression 
do  not  so  commonly  occur,  and  where  a  higher  and  a  more 
top-heavy  instrument  would  be  objected  to,  and  would,  in 
general,  stand  the  chance  of  being  excluded  altogether. 

The  standards  of  the  writer's  Engineer's  Theodolite,  Fig.  75, 
are  only  5  J  inches  in  height,  and  the  range  of  the  semicircle  is 
about  60°  of  depression  to  70°  of  elevation,  sufficient  for  most 
purposes,  especially  in  surface-surveying  operations.  But,  to 
meet  a  few  exceptional  underground  cases,  where  the  angle  of 
depression  amounts  to  70°,  the  instrument  may  be  planted  at 
the  bottom  instead  of  at  the  top  of  the  excavation,  and  the  angle 
so  measured  would  be  equal  to  the  one  of  depression.  In  the 
second  place,  the  limit  for  the  standards  of  this  instrument  is 
from  6f  to  7  inches  in  height;  and,  in  this  case,  the  instrument 
is  capable  of  measuring  an  angle  of  depression  of  66°,  and  one 
of  elevation  of  76°.  However,  if  desired,  the  standards  could 
be  made  7J  inches  high  without  detriment,  and  an  angle  of  ele- 

*  Page  120.  f  Page  100.  J  Page  102. 


REMARKS    ON    MINE-SURVEYING    INSTRUMENTS.  231 

vation  could  then  be  measured  greater  than  76°.  Naturally, 
in  extreme  exceptional  cases,  such  as  those  noted  by  Mr.  Hul- 
bert,*  where  the  dip  ranges  from  83°  to  86°,  special  means 
must  be  employed. 

But  when  a  mineral  vein  has  a  great  dip  "  varying  from  83° 
to  86°,"  as  Mr.  Hulbert  says  was  the  case  in  the  Cliff  mine,  it 
is  an  error  on  his  part  to  state  that  "  no  sight  on  this  inclination 
could  be  taken  with  the  ordinary  transit-telescope."  The  angle 
of  depression  of  any  given  inclined  plane  observed  from  the  top  is 
equal  to  the  angle  of  elevation  of  the  same  plane  measured  from  the 
bottom.  If,  therefore,  an  ordinary  transit-telescope  will  not 
measure  an  angle  of  depression  of  86°,  or  a  larger  angle,  when 
the  standards  of  the  theodolite  are  only  of  a  moderate  height, 
it  will  measure  that  angle  on  the  bottom  of  the  excavation  when 
the  instrument  is  constructed  in  the  form  of  Fig.  74.  f  That 
instrument  is  capable  of  measuring  angles  of  elevation  up  to 
the  zenith;  and  although  the  construction  is  comparatively 
simple,  still  it  is  very  portable  and  handy,  as  also  very  effective. 
It  was  the  favorite  instrument  of  the  writer  in  1858,  and  a  large 
number  were,  and  still  continue  to  be,  constructed  by  various 
English  makers  for  local  and  foreign  use,  especially  in  various 
parts  of  South  America.  It  is,  however,  preferable  when 
mounted  upon  a  triangular  leveling-base  with  three  leveling- 
screws,  as  shown  in  the  diagram  in  the  right  hand  lower  corner 
of  Fig.  74. 

The  writer  has  clearly  explained  how  his  Engineer's  The- 
odolite, Fig.  75, J  can  be  applied  in  order  to  perform  the  work 
of  a  transit-theodolite;  consequently  there  is  no  need  to  give  it 
the  form  Mr.  Scott  suggests,  or  to  introduce  in  it  a  cyclotomic 
circle ;  a  plan,  by  the  way,  that  Mr.  Scott  recommends,  and 
does  not  adopt  for  his  own  instrument.  The  instrument  of  Fig. 
75  is  constructed  with  as'much  perfection  as  the  present  prac- 
tice of  mechanical  and  mathematical  principles  and  skill  will 
admit ;  and  that  fact,  taken  in  connection  with  the  exceptional 
advantages  pointed  out  by  the  scientific  Jury  of  Awards  at  the 
Chicago  Exhibition,  1893, §  advantages  experienced,  too,  in  the 
practice  of  other  engineers  with  the  instrument,  insures  that  it 
is  unrivaled. 

*  Page  147.  f  Page  98.  J  Page  100.  \  Page  97. 


232 


REMARKS    ON    MINE-SURVEYING    INSTRUMENTS. 


However,  if  there  are  persons  who  cannot  be  convinced,  or 
are  not  able  to  appreciate  the  construction  and  use  of  any  other 
instrument  than  a  transit-theodolite,  Fig.  75  may  be  converted 
to  that  form  by  making  the  standards  a  little  higher  than  they 
are  at  present,  shortening  the  object-end  of  the  telescope, 

FIG.  147. 


Hoskold's  Engineer's  Theodolite,  Improved. 

lengthening  its  eye-end,  and  making  the  object-glass  and  eye- 
glass interchangeable ;  so  that  the  instrument  may  be  used  to 
sight  objects  in  the  zenith.  In  this  way,  and  others  to  be 
pointed  out,  may  be  obtained  a  very  effective  and  excellent 
transit-form  of  instrument,  with  the  advantage  that  all  the  other 
parts  may  remain  as  at  present,  Nevertheless,  the  only  ad- 


REMARKS    ON    MINE-SURVEYING    INSTRUMENTS. 


233 


vantage  to  be  gained  by  such  a  change  would  be  the  means  of 
measuring  greater  angles  of  elevation  and  depression,  with  a 
double  transit-effect  for  the  instrument. 

A  general  description  of  the  writer's  Engineer's  Theodolite, 
Fig.  75,  has  already  been  given,  but  the  diagram  illustrating 

FIG.  148. 


Hosk old's  Engineer's  Theodolite,  Improved,  with  Circular  Compass. 

that  description  does  not  represent  the  instrument  as  now  intro- 
duced with  the  ultimate  alterations  and  improvements.  Never- 
theless, the  same  general  type  has  been  preserved.  The  four 
new  diagrams,  Figs.  147,  148,  149  and  150,  exhibit  the  instru- 
ment in  different  positions,  and  present  all  the  details  of  the 
exterior  construction.  A  very  important  alteration  shown  in 


234 


REMARKS    ON    MINE-SURVEYING    INSTRUMENTS. 


Fig.  147  is  the  tubular  or  cylindrical  bearings,  with  circular 
flanges  screwed  to  each  exterior  side  of  the  lower  vertical  axis. 
This  arrangement  enables  the  ends  of  the  lower  horizontal  axis 
to  be  suspended  in  collars  between  adjusting  screws,  further 
from  the  center  of  the  optical  axis  of  the  telescope;  and  so  ef- 

FIG.  149. 


Hoskold's  Engineer's  Theodolite,  Improved.  « 

fectually  prevents  any  possible  lateral  springing  or  vibrating 
effects. 

Another  important  addition  is  the  micrometer,  the  divided  cir- 
cle or  head  of  which  is  seen  at  the  eye-end  of  the  upper  telescope, 
Fig.  150.  This  divided  head  is  attached  to  a  finely-cut  screw 


REMARKS    ON    MINE-SURVEYING   INSTRUMENTS. 


235 


working  in  a  metal  frame  which  carries  the  spider's  line  index, 
over  the  divided  comb,  placed  in  the  micrometer-box  and  in  the 
focus  of  the  telescope.  There  is  nothing  new  in  this  appen- 
dage ;  still,  it  is  exceedingly  useful  and  important  in  measuring 
small  angles  down  to  single  seconds,  and  by  estimation  to  the 

FIG.  150. 


Hoskold's  Engineer's  Theodolite,  Improved. 

half  of  that  quantity,  and  consequently  any  distance  within  the 
range  of  the  telescope  may  be  measured  with  the  greatest 
facility  and  accuracy.  The  simple  trigonometrical  formula  re- 
quired to  effect  the  calculation  of  the  distance  has  already  been 
given.*  Fig.  148  shows  the  manner  of  mounting  the  circular 


Page  116. 


236  REMARKS    ON    MINE-SURVEYING    INSTRUMENTS. 

magnetic  compass  on  top  of  the  telescope.  When  not  so  re- 
quired it  may  be  replaced  by  the  long-trough  magnetic  com- 
pass, the  needle  of  which  has  an  arc  of  only  a  few  degrees — as 
seen  in  Fig.  150  ;  or  a  long  spirit-bubble  may  be  inserted  in 
place  of  the  trough-compass,  if  required. 

The  circular  compass,  Fig.  148,  contains  a  magnetic  needle 
with  a  vernier  mounted  at  each  end  reading  to  15"  of  arc. 
When  a  magnetic  bearing  is  not  required  so  fine,  a  plain  needle 
is  provided  to  take  the  place  of  the  one  with  verniers.  The  plain 
sights  of  this  compass  are  made  very  short  and  in  pairs,  placed 
at  each  side  of  the  compass-box ;  that  is  to  say,  a  fine  sight  and 
an  open  one.  The  open  sight  is  filled  with  glass,  and  cross- 
lines  are  cut  upon  it.  The  sights  are  hinged  on  a  pin  or  axis, 
and  can  be  turned  down. 

Angleometer. — The  instrument  of  Fig.  76*  is  one  of  the  most 
convenient  and  efficient  for  measuring  angles  of  elevation  to 
the  zenith  or  depression  to  the  nadir;  and  consequently,  as 
previously  noted, f  it  is  well  adapted  for  general  mine-surveying. 

Precision  of  Mine- Theodolites. — Mr.  Stanley  saysij  "I  do  not 
think  mine-surveying  so  exact  as  surface."  He  advances  no 
reason  for  such  a  supposition,  but  possibly  is  thinking  of  trigo- 
nometrical surveys ;  neither  is  it  clear  whether  he  attributes 
the  inexactness  to  systematic  carelessness  on  the  part  of  under- 
ground surveyors,  or  to  inferiority  of  the  instruments  employed. 
As  the  writer's  paper  on  this  subject  has  already  mentioned,  he 
proved  §  more  than  thirty  years  ago  that  when  underground 
surveys  are  conducted  in  a  proper  manner,  with  the  use  of 
modern  instruments  of  the  theodolite  class  and  good  line 
measurers,  as  much  accuracy  can  be  obtained  in  an  underground 
survey  as  in  similar,  though  much  less  difficult  and  inconve- 
nient, operations  on  the  surface. 


*  Page  105.  f  Page  107.  J  Page  76. 

\  A  Practical  Treatise  on  Mining,  Land  and  Railway  Surveying,  Engineering,  etc., 
H.  D.  Hoskold,  London,  1863. 


NOTES    ON    MINE-SURVEYING    INSTRUMENTS.  237 


Notes  on  Mine-Surveying  Instruments, 

with  Special    Reference  to  Mr.  Dunbar  D.  Scott's    Paper 

on  their  Evolution,  and  its  Discussion. 

BY   BENJAMIN   SMITH   LYMAN,    PHILADELPHIA,    PA. 

(Canadian  Meeting,  August,  1900.) 

SYNOPSIS.  PAGE 

I.  ANCIENT  HISTORY, 238 

Accepted  Fables  ;  Babylonian  Mapping  ;  First  Surveying. 

II.  COMPASS, 240 

Chinese  Invention ;    Marco  Polo  ;    First   European  Compasses ;    Early 

Knowledge  of  Variation  ;  Plotting  with  the  Compass ;  Hanging-Com- 
pass ;  Supposed  Gravitational  Error  ;  Merit  of  the  Compass. 

III.  TELESCOPE, 244 

Origin  (Koger  Bacon,  Porta,  Digges,  Lippershey,  Galileo)  ;  Improvements 

(Micrometer  and  Cross-Hairs,  Eittenhouse's  First  Telescope,  Platinum 
Cross-Wires,  Telescopic  Sights,  Keflecting  Telescope,  Achromatic  Lens, 
Kellner  Lens  in  Erecting  Telescope,  Inverting  Telescope). 

IV.  THEODOLITE, 262 

Origin  ;  Derivation  of  the  Name. 

V.  TRANSIT, 267 

First  Surveying  Transit ;  Edmund  Draper. 

VI.  INSTRUMENT-PARTS, 270 

Ramsden's  Dividing  Engine  ;  Fineness  of  Graduation  ;  Conical  Gradua- 
tions ;  Full  Vertical  Circle  ;  Leveling-Screws  ;  Shifting  Tripod-Heads  ; 
Hoffman-Harden  Tripod-Head  ;  Heller  &  Brightly's  Improvements. 

VII.  OTHER  INSTRUMENTS  AND  APPLIANCES,       ......  281 

Sunflower  ;  Plummet-Lamp  ;  Chains  and  Tapes. 

VIII.  SCOTT'S  TACHYMETER, .285 

IX.  NOMENCLATURE  AND  CLASSIFICATION, 286 

Names  ;  Grouping. 

SURVEYORS  are  much  indebted  to  Mr.  Scott  for  so  vigorously 
attacking  the  subject  of  the  origin  and  history  of  mine-survey- 
ing instruments,  the  compass,  the  telescope,  the  transit  and 
other  apparatus.  He  is  not  afraid  of  the  dark,  nor  yet  fool- 
ishly bashful  in  broad  daylight.  He  does  not  recoil  from  the 
obscurities  of  the  earliest  times  and  the  most  difficult  historical 
points ;  and,  with  commendable  public  spirit,  he  makes  his  own 
invention  known  to  his  fellow-workers,  and  challenges  their 
criticism.  He  has,  moreover,  elicited  the  praiseworthy  emula- 


238  NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 

tion  of  Mr.  Hoskold.  They  both  quote  from  rare  old  books, 
two  or  three  of  which  are  to  be  found  in  our  great  Philadelphia 
and  New  York  libraries,  enabling  us  to  ascertain  yet  a  few  facts 
that  bear  in  an  interesting  way  on  the  origin  of  the  instruments 
and  of  some  of  their  essential  parts. 

I.  ANCIENT  HISTORY. 

Accepted  Fables. — Mr.  Scott  and  Mr.  Hoskold  dip  into  early 
Oriental  history,  but  cite  only  authorities  that  are  antiquated 
without  being  ancient.  Our  few,  but  very  learned  Philadelphia 
Assyriologists  and  Egyptologists  declare  they  have  little  faith 
in  the  existence  of  any  Assyrian  or  Egyptian  surveying  instru- 
ments. Proclus,  about  A.D.  450,  in  his  history  of  geometry  be- 
fore the  time  of  Euclid,  begins  with  what  Prof.  A.  de  Morgan* 
justly  characterizes  as  "  absurd  stories :"  how  the  Egyptians 
invented  geometry,  or  surveying,  as  a  means  of  recovering  land- 
marks destroyed  by  the  annual  Nile  floods,  and  Thales  (say 
600  B.C.)  brought  the  knowledge  to  Greece.  The  oft-repeated 
tale  has  so  little  internal  evidence  to  give  it  any  probability  in 
the  eyes  of  a  practical  surveyor,  that  it  is  surprising  to  see  it 
approvingly  cited  from  Alfarabius,  the  famous  Arabian  scholar 
of  the  10th  century,  by  Jakob  Koebel  in  his  G-eometrey  von  Kiinst- 
lichem  Feldmessen,  the  book  referred  to  by  Mr.  Brough  (see 
the  New  York  Astor  Library  copy  of  1593).  When  we  con- 
sider that  the  doubtless  far  more  highly  enlightened  Japanese 
did  little  or  nothing  in  the  way  of  precise  surveying  until  about 
100  years  ago,  and  then  with  some  knowledge  of  European 
methods,  and  even  much  later  were  mostly  contented  with  mere 
sketch  maps  of  the  roughest  kind ;  and  that  it  has  been  the 
same  with  the  decidedly  more  advanced  Chinese,  except  for  the 
mapping  introduced  by  the  Jesuit  missionaries ;  we  may  well 
doubt  whether  those  early  ancients  accomplished  anything  bet- 
ter, or  used  for  the  purpose  any  instruments  of  precision. 

Babylonian  Mapping. — That  doubt  is  fully  confirmed  by  Fig. 
151, f  a  photographic  copy  of  the  best  Babylonian  map  that  has 
yet  been  discovered,  a  map  of  the  world,  not  newer  than  about 
650  B.C.,  a  very  rude  affair  indeed,  that  could  have  required  no 

*  Smith's  Dictionary  of  Greek  and  Roman  Biography,  under  Eucleides. 
t  Copied  from  Prof.  Paul  Haupt's  paper  in   Ueber  Land  und  Meer,  Dec.,  1895, 
vol.  Ixxiii.,  No.  15,  p.  348. 


NOTES    ON    MINE-SURVEYING    INSTRUMENTS.  239 

instruments  of  precision  beyond  the  blunt-pointed  dividers  with 
which  the  .outside  concentric  circles,  representing  the  ocean, 
were  drawn  on  the  clay  tablet. 

Prof.  Haupt  explains  that  the  points  or  triangles  projecting 
from  the  outer  circles  are  marked  as  islands,  and  appear  to 
have  been  originally  seven  in  number.  To  the  left  of  each  is- 
land its  distance  is  exactly  given,  and  to  the  northeastern  one 
is  added :  "  Six  hours  the  sun  is  not  seen."  The  smaller  circles 
indicate  cities  of  the  Euphrates  region.  The  two  long  parallel 
curved  lines  from  above  downwards  are  for  the  Euphrates ;  and 
the  long  parallelogram  crossing  it  is  Babylon,  on  both  banks. 

FIG.  151. 


Babylonian  Map-Tablet,  about  J  Full-size. 

Plainly,  no  great  cartographic  skill  is  here  displayed ;  and  it  is 
hard  to  believe  that  even  rude  angle-measuring  surveying-in- 
struments could  at  that  time  have  been  in  use  in  that  country. 
First  Surveying. — Undoubtedly,  however,  land  was  much  ear- 
lier measured  by  rods  or  cords ;  and  that  must  have  been  the 
beginning  of  land-surveying.  Perhaps  the  earliest  allusion  to 
land-surveying  in  any  language  is  where  Homer,  about  900  B.C.,* 
compares  the  zeal  and  vigor  of  the  Greek  and  Trojan  critical 
battle  at  the  rampart  near  the  ships  to  the  eagerness  of  a  con- 
test between  two  men,  measures  in  hand,  over  the  boundary  that 

*  Iliad,  xii.,  421-426. 


240  NOTES    ON    MINE-SURVEYING    INSTRUMENTS. 

is  to  divide  land  that  had  been  held  in  common.  He  makes  it 
very  evident  that  the  rude  surveying  of  those  days  left  much  to 
mere  opinion  as  to  the  equitable  division  of  a  piece  of  ground, 
and  that  there  was  nothing  like  an  authoritative  county  sur- 
veyor at  hand  to  settle  the  dispute.  Closely  rendered,  the  pas- 
sage says : 

As  two  men  over  bounds  will  stiffly  strive 
With  rood  in  hand  upon  a  common  field, 
And  in  a  narrow  plot  claim  each  his  share  : 
So  battlements  part  these  ;  but  they,  atop, 
Smite  hard  before  each  other's  breast  the  targe 
Well-orbed  of  oxhide,  or  the  buckler  light. 

II.  COMPASS. 

Chinese  Invention. — The  invention  of  the  compass  has  been 
claimed  for  the  very  early  .Chinese ;  but  von  MoellendorfF,  an 
excellent  authority,  declares*  that  the  wet  compass  has  not  been 
proved  to  exist  in  China  before  our  12th  century ;  and  that  the 
dry  compass  was  introduced  there  from  Japan,  and  to  Japan 
from  Europe. 

Marco  Polo. — As  for  the  introduction  of  the  compass  into 
Europe  by  Marco  Polo,  mentioned  by  Mr.  Scott,  it  is  not  nec- 
essary to  do  more  than  quote  a  single  sentence  from  Yule, 
the  highest  authority  in  regard  to  Polo.  He  saysf :  "  Re- 
specting the  mariner's  compass  and  gunpowder  I  shall  say 
nothing,  as  no  one  now,  I  believe,  imagines  Marco  to  have  had 
anything  to  do  with  their  introduction." 

First  European  Compasses. — The  use  of  the  compass,  if  really 
first  invented  in  China,  appears,  then,  to  have  quickly  spread 
through  Europe,  according  to  the  early  history  of  the  compass 
in  Europe  as  given  pretty  thoroughly  in  Nature,  by  "  K.,"J  and 
by  Wm.  Chappell.§  Chappell  shows  that  the  earliest  European 
mention  of  the  compass  is  by  Alexander  Neckham,  an  English 
monk  and  writer  of  elegant  Latin  in  the  12th  century,  who  was 
born  about  1150  and  died  in  1227.  Neckham  speaks  of  the 
compass  in  his  treatise  De  Utensilibus,  and  yet  more  clearly,  as 
a  thing  already  in  common  use,  in  another  treatise,  De  Naturis 
Rerum.  He  describes  it,  not  as  floating  in  water,  but  as  turning 

*  Zeitschrift  der  Morgenlaendischen  Gesellschaft,  1881,  vol.  xxv.,  p.  76. 
f  The  Book  of  Ser  Marco  Polo,  vol.  i.,  Introduction,  p.  clvi.,  1871. 
t  Vol.  xiii.,  Apr.  27,  1876,  p.  523. 
%  Vol.  xiv.,  June  15,  1876,  p.  147. 


NOTES    ON    MINE-SURVEYING    INSTRUMENTS.  241 

on  a  pivot  without  any  special  box  for  it.  That  seems  to  show 
that  it  was  not  introduced  from  China  ;  and,  rather,  the  floating 
form,  soon  after  common  in  Europe,  was  perhaps  first  carried 
thence  to  China.  The  earliest  previously  known  European 
mention  of  the  magnetic  needle  was  in  the  poem  called  the 
Bible  of  Guiot  de  Provins,  composed  in  the  13th  century,  where 
a  rude  floating  compass  is  clearly  indicated.  The  Encyclo- 
paedia Britannica  also  cites  Cardinal  Jacques  de  Vitry's  History, 
written  about  1218,  as  speaking  of  the  magnetic  needle  as 
"  most  necessary  for  such  as  sail  the  sea."  A  little  later,  fre- 
quent allusions  to  it  occur,  and  before  the  middle  of  the  13th 
century,  as  a  generally  well-known  implement.  Already,  about 
1597,  Wm.  Barlowe  denounced  "  the  lame  tale  "  that  Flavio 
Gioja  of  Amalfi  about  1302  invented  the  compass  as  "  of  very 
slender  probabilitie."  But  the  tale  persisted  until  the  present 
century ;  and,  against  the  claims  of  the  French  to  the  invention 
of  the  compass,  based  on  the  fleur-de-lis  upon  it,  the  answer  is 
made  that  Gioja  "  decorated  the  north  end  of  the  needle  with 
that  flower  in  compliment  to  his  own  sovereign,  who  bore  it  in 
his  arms,  as  being  descended  from  the  royal  house  of  France." 

Early  Knowledge  of  Variation. — According  to  "  K.,"  a  Latin 
letter  ascribed  to  Peter  Adsiger,  1269,  speaks  plainly  of  the  va- 
riation of  the  compass,  or  magnetic  declination.  The  dip  of 
the  needle  was,  according  to  "  K.,"  first  discovered  as  early  as 
1576  by  Robert  Norman,  a  nautical-instrument  maker  at  Wap- 
ping,  near  London ;  and  in  the  early  part  of  the  next  century 
the  variation  of  the  declination  was  clearly  ascertained,  and  by 
Bond,  a  teacher  of  navigation  in  London,  attributed  to  the  mo- 
tion of  two  magnetic  poles  of  the  earth. 

Plotting  with  the  Compass. — The  ordinary  and  occasional  ex- 
tent of  the  diurnal  changes  of  the  declination  seems  hardly  to 
be  familiarly  known  to  those  geometers  who  imagine  that  it  is 
exquisite  nicety  to  plot  compass-notes  with  the  help  of  the  very 
compass  used  in  the  field-work,  instead  of  simply  using  a  pro- 
tractor. Aside  from  the  delay  required  by  the  vibrating  needle 
and  the  possible  influence  of  the  friction  at  the  centerpin  of  a 
compass  not  in  the  very  best  condition,  the  daily  change  of  the 
declination  is  very  notable.  The  declination  was  found  by 
Burt  in  July,  1839,*  to  change  within  seven  hours  and  a  half 

*  See  his  Key  to  the  Solar  Compass,  1858,  p.  27. 


242  NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 

sometimes  as  much  as  20  minutes,  sometimes  only  two  minutes ; 
but  the  average  of  his  18  consecutive  days  of  three  observa- 
tions daily  is  14  minutes  of  change  in  the  same  7J  hours. 
A.  Beyer,*  as  cited  by  Combes,f  found  the  needle  to  vary  30 
minutes  between  noon  and  midnight,  June  4,  1736.  I  have 
myself  seen  a  change  of  about  30  minutes  in  14  hours,  in  Cape 
Breton.  Plainly,  if  the  plotting  of  a  note  should  not  happen  to 
be  at  a  moment  when  the  variation  was  the  same  as  it  was  at 
the  time  of  making  the  field  observation,  the  plotting  would 
have  an  error  that  might  be  important.  On  the  other  hand,  in 
using  the  simple  protractor,  there  should  be  no  occasion  for 
notable  error,  leaving  merely  the  original  and  necessarily  in- 
herent errors  of  the  compass  in  the  field,  that  more  or  less  bal- 
ance one  another. 

Hanging- Compass. — It  is  not  a  little  surprising  to  learn  from 
Messrs.  Hungerford's  and  Johnson's  contributions  to  the  dis- 
cussion that  the  hanging-compass  has  been  found  on  the  whole 
not  only  practicable,  but  the  most  convenient  instrument  for 
surveying  tortuous,  steep,  narrow  underground  workings  in 
Virginia.  One  would  have  thought  that  a  compass  on  a  suf- 
ficiently small  tripod  would  be  not  only  more  satisfactory  in 
result,  but  more  expeditious  in  use,  than  apparatus  that  requires 
so  much  circumstance  as  driving  in  nails,  stretching  a  cord, 
hanging  up  the  compass  and  waiting  for  the  cord  vibrations  to 
diminish  enough  to  make  it  safe  to  loosen  the  needle.  We 
have  been  accustomed  to  smile,  perhaps  too  superciliously,  at 
this  old-world  method,  and  to  think  its  users,  even  the  profes- 
sors at  Paris  and  Freiberg  forty  years  ago,  were  one  or  two 
hundred  years  behind  the  times ;  with  their  gradbogen,  too,  and 
with  their  square  compass  (boussole  carree\  with  its  telescope  at 
one  side  and  their  consequent  ingenious  elaborate  computa- 
tions to  obviate  the  difficulty  of  the  eccentricity  of  the  sight, 
instead  of  using  simply  a  lop-sided  target. 

Supposed  Gravitational  Error. — Mr.  Hoskold  argues J  that  the 
compass  is  inexact  because  the  plumb-line  in  India  and  else- 
where has  been  found  to  be  affected  by  the  gravitational  attrac- 
tion of  neighboring  mountain  masses  or  of  especially  dense 

*  Griindlicher  Unterricht  vom  Bergbau  nach  Anleitung  der  Markscheidekunst.  Alten- 
burg,  1785.  f  Annoles  des  Mines,  1836,  Troisieme  S^rie,  vol.  ix.,  p.  98. 

t  Page  222. 


NOTES    ON    MINE-SURVEYING   INSTRUMENTS.  243 

neighboring  portions  of  the  earth's  crust ;  and  that  the  prob- 
able effect  was  in  advance  estimated  for  the  extreme  case  of 
the  Himalayas  as  likely  to  be  as  much  as  almost  half  a  minute, 
though  it  turned  out  after  all  to  be  "  much  smaller  "  than  the 
estimate,  and  in  some  places  quite  reversed  in  direction.  He 
infers  that,  as  the  needle  hangs  upon  the  top  of  a  centerpin,  it 
should  be  affected  in  the  same  way  as  the  plumb-line.  Even 
admitting  that  it  were  so,  it  is  obvious  that  the  very  short 
length  from  the  ends  of  the  needle  up  to  the  level  of  its  point 
of  suspension,  say  a  sixteenth  of  an  inch,  would  make  the  arc 
through  which  the  needle  swings  extremely  short,  in  fact  com- 
pletely invisible,  even  if  its  angular  amount  were  half  a  minute, 
and  even  if  its  direction  were  at  right  angles  to  the  length  of 
the  needle. 

Of  course,  as  the  needle  is  balanced  upon  the  centerpin,  one 
end  would  be  attracted  by  the  gravity  of  the  mountain  or  dense 
mass  of  rock  as  much  as  the  other  end,  so  that  there  would  be 
no  effect  in  that  way  upon  the  indication  of  the  needle.  On 
one-half  of  the  needle,  however,  there  is  a  small  bit  of  brass 
wire  to  counteract  the  dip  that  is  different  in  different  latitudes. 
That  minute  additional  weight  would  be  attracted  towards  the 
mountain  or  dense  rocks ;  but  even  supposing  that  the  very 
feeble  or  infinitesimal  attraction  is  enough  to  overcome  the  at 
best  slight  friction  at  the  centerpin,  and  resist  the  probably  far 
stronger  magnetic  directive  force  of  the  earth  (perhaps  as  much 
stronger  as  the  weight  of  a  plumb-bob  would  be  compared  to 
the  sidewise  pull),  and  that  the  attraction  works  at  right  angles 
to  the  longitudinal  axis-  of  the  needle  and  to  the  highest  com- 
puted amount  of  nearly  half  a  minute,  even  Mr.  Hoskold's 
vernier  on  the  needle  for  reading  quarter-minutes  could  scarcely 
in  any  single  reading  appreciate  the  difference  caused. 

As  mountain  masses  like  the  Himalayas  are  extremely  rare, 
and  as  their  observed  effect  upon  the  plumb-line  proved  to  be 
"  much  smaller  "  than  half  a  minute,  the  error  from  gravita- 
tional attraction  upon  the  needle  in  any  ordinary  survey  would 
clearly  be  quite  inappreciable,  even  if  the  needle  were  per- 
fectly precise  in  its  indications.  When  we  consider  the  well- 
known  fact  that  the  needle  for  magnetic  reasons  is  liable  to 
vary  two  or  three  minutes  in  one  hour,  it  is  evident  that  in 
using  the  needle  at  all,  the  consideration  of  the  at  most  alto- 

17 


244  NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 

gether  invisible  and  immeasurable,  and  moreover  wholly  doubt- 
ful and  certainly  incalculable,  gravitational  effect  would  be  like 
straining  out  the  gnat  while  ready  to  swallow  the  camel.  The 
same  may  be  said,  too,  of  Mr.  Hoskold's  other  idea  of  undertak- 
ing to  read  the  needle  to  a  quarter  of  a  minute  with  a  vernier  ! 
Merit  of  the  Compass. — The  merit  of  the  needle  is  not  the 
extreme  precision  of  its  indication  in  any  single  reading ;  but 
that  it  refers  at  each  reading  independently,  within  a  very  few 
minutes  of  arc,  to  an  invariable  meridian,  so  that  any  errors, 
whether  inherent  in  the  compass,  or  coming  from  insufficient 
care  in  reading  or  noting,  do  not,  like  the  errors  of  vernier-plate 
running,  swing  all  the  subsequent  courses  of  the  survey  around. 
The  secular  variation  can  be  allowed  for,  and  the  diurnal 
changes,  if  not  roughly  corrected  by  the  Coast  Survey  table,* 
still  tend  to  balance  one  another.  Indeed,  the  five-inch  com- 
pass compares  reasonably  well  for  accuracy  with  excellent  ordi- 
nary chaining,  or  even  with  the  yet  more  exact  telescopically 
read  stadia-measurement,  or  with  plotting  mechanically  on  a 
scale  of,  say,  400  feet  to  an  inch  (not  by  latitudes  and  departures 
computed  with  five-place  or  larger  logarithms).  It  is  not  an 
instrument  capable  of  the  utmost  precision  for  geodetic  pur- 
poses, for  city  surveying,  for  tunnel-driving  and  the  like  ;  but 
it  is  extremely  useful  for  other  much  more  numerous,  in  the 
aggregate  far  more  extensive,  and  perhaps,  on  the  whole,  more 
important  surveys,  where  the  very  nicest  precision  is  unneces- 
sary and  would  require  extravagant  expense. 

III.  TELESCOPE. 

Origin. — The  common  accounts  of  the  origin  of  the  telescope 
are  mostly  copied  one  from  another,  without  the  least  attempt 
at  any  independent  critical  judgment.  There  is,  however,  an 
easily  accessible,  very  thorough  discussion  in  Dr.  Robert 
Grant's  History  of  Physical  Astronomy,  London,  1852 ;  and  a 
later  discriminating  one  by  Dr.  David  Grill,  Astronomer  Royal, 
Cape  of  Good  Hope,  in  the  Encyclopaedia  Britannica,  9th  edi- 
tion (1888),  and  a  briefer  notice  in  Chambers'  Encyclopedia 
(1892). 

The  first  discovery  of  the  telescope  has  been  variously  at- 
tributed to  Roger  Bacon,  before  1294,  Giambattista  della  Porta, 

*  Given  in  Heller  &  Brightly's  Remarks  on  Surveying  Instruments,  1882,  p.  13. 


NOTES    ON    MINE-SURVEYING   INSTRUMENTS.  245 

1561,  Leonard  Digges  before  1570,  three  Dutchmen  in  1608, 
and  Galileo  in  1609.  A  careful  fresh  revision  of  the  evidence 
will  make  it  clear  that  Bacon  and  Porta  knew  nothing  of  the 
telescope,  that  Digges  really  did  invent  and  use  a  reflecting 
telescope,  but  that  Lippershey,  one  of  the  three  Dutchmen,  was 
the  first  to  make  a  refracting  telescope,  and  that  Galileo  rein- 
vented it. 

Roger  Bacon. — Two  citations  in  particular  from  Friar  Roger 
Bacon,  "  the  Admirable  Doctor,"  who  died  about  1294,  have 
been  claimed  to  show  clearly  that  he  had  at  least  a  theo- 
retical knowledge  of  the  telescope;  but  they  seem  really  to 
apply  at  best  merely  to  single  lenses,  and  nothing  that  he  says 
necessarily  indicates  any  combination  of  lenses. 

All  the  passages  have  been  carefully  examined  by  a  very 
competent  critic,  Eobert  Smith,  LL.D.,  in  his  Compleat  System 
of  Opticks,  Cambridge,  1738.  He  says  that  Bacon,  in  his  Opus 
Majus,  having  described  several  canons  of  refraction  through  a 
plane  and  a  spherical  surface,  applies  them  to  the  explanation  of 
several  appearances  (doubtless  familiar  from  the  earliest  times) ; 
such  as,  why  an  oar  partly  in  the  water  appears  crooked,  and 
why  a  coin  in  the  bottom  of  a  basin,  hidden  from  the  eye  by 
the  side  of  the  basin,  becomes  visible  on  pouring  in  water ; 
and  that  Bacon  then  adds  a  passage  which  Smith  cites  in  full 
with  its  diagrams,  essentially  to  the  following  effect : 

"  If  a  man  should  look  at  letters  or  any  minute  objects  through  the  medium  of 
a  crystal,  or  glass,  or  other  transparent  body  placed  upon  the  letters  ;  and  it 
should  be  the  segment  of  a  sphere  of  which  the  convexity  is  towards  the  eye,  and 
the  eye  should  be  in  the  air,  he  will  see  the  letters  better  and  they  will  appear 
larger  to  him  ;  .  .  .  and  therefore  this  instrument  is  useful  to  old  men  and  to 
those  that  have  weak  eyes.  .  .  .  But  if  it  be  the  larger  segment  of  a  sphere,  or 
but  half  of  one,  then,  by  the  sixth  canon,  there  will  be  an  enlargement  of  the 
visual  angle  and  an  enlargement  of  the  image,  but  nearness  will  be  lacking,  be- 
cause the  place  of  the  image  is  beyond  the  object.  And  therefore  this  instrument 
is  not  so  effective  (non  ita  valet)  as  the  lesser  segment  of  a  sphere." 

It  is  noticeable  that  the  segment  rests  immediately,  flatwise, 
upon  the  letters,  and  there  is  nothing  said  of  a  refraction  at 
both  the  surfaces.  Smith  translates  "  non  ita  valet "  by  "  not  so 
powerful  in  magnifying,"  and  argues  that  Bacon  showed  thereby 
his  ignorance  of.  the  real  effect  of  the  lens,  and  consequently 
never  could  actually  have  used  one  ;  and  adds : 

11  As  to  his  theory  and  applications  abovementioned,  they  are  all  taken  from 
Alhazen,  whom  he  frequently  mentions  upon  other  occasions.  Alhazen  is  reckoned 


246  NOTES    ON    MINE-SURVEYING    INSTRUMENTS. 

to  have  lived  about  the  year  of  our  Lord  1100  [born  at  Basso  ra,  and  died  at  Cairo 
about  1038].  Among  his  experiments  made  to  confirm  his  theorems,  he  expressly 
mentions  that  if  an  object  be  applied  close  to  the  base  of  a  larger  segment  of  a 
sphere  of  glass,  it  will  appear  magnified  ;  which,  as  I  observed,  was  fitter  for 
Bacon's  purpose  than  his  own  lesser  segment.  He  also  treats  about  the  appear- 
ance of  an  object  through  a  globe  ;  and  says  he  is  the  first  that  found  out  the 
refraction  of  rays  into  the  eye." 

The  magnifying  effect  of  a  glass  globe  on  near  objects  could, 
however,  scarcely  have  failed  to  be  noticed  long  before  Alhazen. 
Indeed,  a  passage  in  Aristophanes  (Clouds,  Act  II.,  Scene  1) 
clearly  indicates  a  common  knowledge  of  burning-glass  lenses 
among  the  ancient  Greeks,  423  B.C.,  150  years  before  the  time 
of  Archimedes'  mythical  exploit  of  ship-burning  with  a  glass. 

But  when  Bacon  uses  the  words  "  non  ita  valet,"  he  has  just 
distinctly  acknowledged  the  greater  size  of  the  image,  and  with 
those  words  he  explains  that,  after  all,  owing  to  the  greater  dis- 
tance of  the  image,  the  instrument  is  less  effective,  meaning 
apparently  not  in  magnifying  power,  but  in  definition,  and 
therefore  less  useful  in  the  general  result.  The  increased  thick- 
ness of  the  glass  would  add  to  the  spherical  and  chromatic  ab- 
errations, and  with  the  impure  glass  of  the  12th  century  (when 
"uncolored"  glass  was  greenish,  with  many  bubbles),  the  greater 
thickness  would  to  some  extent  bedim  the  view ;  and  the  ob- 
scure result  might  conceivably  have  been  attributed  to  the 
greater  distance  of  the  image.  It  looks,  then,  rather  as  if 
Bacon  did  really  try  such  lenses,  large  segments  of  glass  spheres 
of  some  size. 

The  practice  of  laying  such  a  lens  flatwise  immediately  upon 
letters,  for  the  convenience  of  old  or  weaksighted  men,  may  well 
have  been  the  first  step  towards  the  invention  of  spectacles,  a 
discovery  destined  to  be  of  such  immense  importance  to  elderly 
people,  and  almost  equivalent  to  a  prolongation  of  their  lives 
by  many  years.  Indeed,  Smith,  although  regarding  Bacon's 
words  as  mere  theoretic  speculations,  and  incorrect  ones,  con- 
siders, possibly  with  some  patriotic  feeling,  that  they  gave  the 
first  hint  towards  the  invention ;  and  in  corroboration  makes 
certain  citations  in  other  quarters,  showing  that  spectacle- 
glasses  were  invented  between  1285  and  1300.  For  instance, 
Friar  Jordan  de  Eivalto,  who  died  at  Pisa  in  1311,  is  said  to 
have  written,  in  a  book  of  sermons  in  1305,  that  it  was  not 
twenty  years  since  the  art  of  making  spectacles  was  found  out ; 


NOTES    ON    MINE-SURVEYING    INSTRUMENTS.  247 

and  an  Italian  manuscript  of  1299  in  Redi's  library  says  they 
had  lately  been  invented  for  the  convenience  of  poor  old  men 
with  failing  power  to  read.  Friar  Alexander  de  Spina,  who 
died  at  his  native  city  of  Pisa  in  1313,  is  said  by  a  Latin  chron- 
icle there  to  have  first  published  spectacle-glasses  between  1280 
and  1311,  not  as  his  own  invention,  but  the  discovery  of  some- 
body else  who  would  not  make  them  public.  Smith  not  un- 
reasonably conjectures  that  other  "  close  man  "  to  have  been  a 
friar ;  "  and  that  these  monkish  men,  and  Jordan  amongst  the 
rest,  had  this  invention  whispered  amongst  themselves,  before 
it  was  publick ;  and  that  they  all  had  the  first  hint  thereof  from 
our  country-man  Frier  Roger  Bacon." 

The  passage  in  the  Opus  Majus  specially  used  to  support  the 
claim  that  Roger  Bacon  combined  lenses  into  a  telescope  says : 

"  We  can  give  such  figures  to  transparent  bodies,  and  dispose  them  in  such 
order  with  respect  to  the  eye  and  the  object  that  the  rays  shall  be  refracted  and 
bent  towards  any  place  we  please.  So  that  we  shall  see  the  object  near  at  hand  or 
under  any  angle  we  please.  And  thus  from  an  incredible  distance  we  may  read 
the  smallest  letters,  and  may  number  the  smallest  particles  of  dust  and  sand,  by 
reason  of  the  greatness  of  the  angle  under  which  we  see  them." 

Smith  argues  that  the  passage  indicates  that  Bacon 

"  did  not  think  of  performing  these  problems  by  a  single  portable  instrument  like 
a  telescope,  but  by  fixing  up  several  glasses  in  proper  places  at  large  intervals  from 
one  another  [much  as  he  had  in  the  foregoing  chapter  explained  that  mirrors 
might  be  arranged  so  as  to  multiply  a  single  soldier  into  an  army  in  appearance]  ; 
which  would  certainly  prove  ineffectual.  .  .  .  Mr.  Molyneux  says  it  is  manifest 
he  knew  what  a  concave  and  a  convex  glass  was.  But  this  does  not  appear 
from  the  passage  there  cited,  nor  from  any  other  that  I  have  yet  met  with.  .  .  . 
In  short,  the  author  speaks  only  hypothetically,  saying  that  glasses  may  be  fig- 
ured, and  objects  may  be  magnified  so  and  so  ;  but  never  asserts  one  single  trial 
or  observation  upon  the  sun  or  moon  (or  any  thing  else)  though  he  mentions  them 
both.  On  the  other  hand  he  conceives  some  effects  of  telescopes  that  cannot  pos- 
sibly be  performed  by  them." 

It  seems  that  the  passage  just  quoted  from  Bacon  might  re- 
fer merely  to  the  possible  or  conceivable  change  of  direction  in 
rays  by  means  of  a  prism,  or  perhaps  of  a  combination  of 
prisms  (though  the  words  do  not  clearly  indicate  that  any  com- 
bination is  meant),  and  to  the  enlargement  possible  by  means 
of  the  segment  of  a  sphere,  or  rude  lens,  whose  use  had  been 
already  described,  and  whose  effect,  then  so  novel,  may  natu- 
rally have  been  set  forth  in  language  that  would  now  seem  ex- 


248  NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 

aggerated.  The  words  do  not  necessarily  imply  a  combination 
of  more  than  one  glass  at  a  time.  There  is,  then,  110  sufficient 
reason  to  believe  that  Roger  Bacon  ever  used  a  telescope,  or 
even  any  nearer  approach  to  a  spectacle-lens  than  a  very  thick 
spherical  segment  of  impure  glass  applied  close  to  the  letters 
read. 

Porta. — A  citation  from  Giambattista  della  Porta's  Magia 
Naturalis,  printed  in  1558-89,  in  the  X^IIth  Book,  apparently 
published  in  1561,  contains  expressions  that  have  been  taken  to 
prove  that  he  used  a  telescope ;  but  it  has  also  been  said  that 
grave  doubts  have  been  thrown  upon  Porta's  knowledge  and 
originality  by  such  high  authorities  as  Kepler  and  Poggendorff. 
All  Porta's  claims  to  the  invention  of  the  telescope  have,  to  be 
sure,  their  foundation  in  what  Kepler  says  and  quotes  of  Porta  in 
a  charming,  generously  appreciative  letter  to  Galileo,  published 
in  1610,  and  written  after  receiving  in  Galileo's  Nuncius  Sidereus 
the  account  of  the  re-invention  of  the  telescope  and  the  first 
astounding  telescopic  astronomical  discoveries,  the  four  moons 
of  Jupiter,  the  diversified  appearance  of  the  moon's  surface, 
the  distinctly  orbicular  shape  of  the  planets,  the  tenfold  increase 
of  visible  stars,  the  resolution  of  nebulae  in  the  milky  way  into 
stars,  and  the  like. 

The  common  short  notices  give  so  imperfect  and  inconclusive 
and  apparently  so  inaccurate  an  account  of  Porta's  statements 
and  of  Kepler's  comments  on  them,  and  even  Kepler  himself 
so  seems  to  misinterpret  Porta,  and  the  original  is  so  difficultly 
accessible  to  most  of  our  members,  that  it  is  probably  worth 
while  to  give  here  the  whole  passage  from  Kepler's  letter;  the 
more  so,  as  it  shows  in  a  striking  light  how  far  even  the  ablest 
astronomers  and  physicists  of  those  times  had  been  from  real- 
izing the  possibility  of  anything  like  a  telescope,  simple  and 
natural  as  such  an  application  of  the  well-known  laws  of  optics 
seems  nowadays.  Kepler  appears  to  say,  in  pretty  literal  trans- 
lation (and  for  greater  certainty  the  more  essential  part  of  the 
original  Latin  is  given  below) :  * 

"Incredible  to  many  seems  the  undertaking  of  so  effective  a  spyglass  ;  but  im- 
possible or  new  by  no  means  is  it ;  nor  did  it  lately  first  proceed  from  the  Dutch, 

*  Opere  di  Galileo,  Florence,  1892,  vol.  iii.,  p.  108  : 

•'Incredibile  multis  videtur  epichirema  tarn  efficacis  perspicilli,  at  impossibile 


NOTES    ON    MINE-SURVEYING   INSTRUMENTS.  249 

but  already  a  number  of  years  ago  it  was  published  by  lo.  Baptista  Porta  in 
Natural  Magic,  Book  XVII,  Chap.  X,  On  the  Properties  of  the  Crystal  Lens. 
And  that  it  may  appear  that  not  even  the  arrangement  of  a  concave  and  a 
convex  lens  is  new,  come,  let  us  bring  forward  the  words  of  Porta.  He  writes 
thus  : 

' '  With  the  eye  placed  in  the  center,  behind  the  lens,  whatever  was  remote  you  will  see 
so  near  that  you  would  seem  to  touch  it  with  the  hand,  or  that  you  will  recognize  friends 
that  are  very  distant :  letters  of  an  epistle  placed  at  a  due  distance  you  will  see  so  large 
that  you  can  clearly  read  :  if  you  incline  the  lens,  so  as  to  look  at  the  epistle  obliquely, 
you  will  see  the  letters  sufficiently  large  to  read  them  even  at  a  distance  of  twenty  paces  : 
and  if  you  know  how  to  multiply  the  lenses,  I  doubt  not  but  that  you  would  see 
the  smallest  letter  at  a  hundred  paces,  so  that  from  one  into  another  the  characters 
may  be  rendered  larger.  Let  defective  sight  use  glasses  according  to  the  quality  of  the 
sight.  Whoever  should  understand  how  to  make  that  adaptation  rightly  will  get  a  secret 
that  is  not  small.  Concave  lenses  make  whatever  is  distant  to  be  seen  very  clearly, 
convex  ones  what  is  near,  wherefore  you  can  enjoy  them  according  to  their  adaptation  to 
your  vision.  With  a  concave  lens  you  see  small  things  at  a  distance,  but  distinctly ; 
with  a  convex  one,  you  see  near  things  larger,  but  indistinctly :  if  you  know  how  to 
arrange  each  rightly,  you  will  see  both  distant  and  near  things  larger  and  clearly.  Not 
a  little  aid  have  I  given  to  many  friends  who  saw  both  distant  things  dimly  and  near  ones 
indistinctly,  so  that  they  saw  everything  most  perfectly.  So  much  from  Chap.  X. 

"  In  Chapter  XI  he  makes  a  new  title  on  glasses  with  which  beyond  all 
thought  any  one  can  see  very  far  ;  but  he  so  involves  the  demonstration  (which 
he  even  admits),  that  you  would  not  know  what  he  says,  whether  he  is  speaking 
of  transparent  lenses,  as  hitherto,  or  indeed  adds  an  opaque  smooth  mirror :  of 
which  even  I  myself  have  one  in  mind,  which  shows  remote  things,  with  no  dif- 
ference of  distance,  in  very  great  size,  and  therefore  near  and  moreover  propor- 
tionally enlarged,  with  as  much  clearness  as  can  be  hoped  for  from  a  mirror 
(which  necessarily  gives  a  dim  color). 

"  When  to  this  part  of  Porta' s  book  I  saw  the  complaint  prefixed  at  the  begin- 
ning of  Chapter  X,  that  of  concave  and  convex  lenses  and  glasses,  so  greatly  necessary 
for  human  uses,  no  one  had  yet  brought  forward  the  effect  or  the  explanations,  I  under- 
took that  work  six  years  ago  in  the  Optical  part  of  my  Astronomy,  so  as  to  set 
forth  with  a  clear  geometrical  demonstration  what  occurs  in  simple  lenses. 

aut  novum  nequaquam  est ;  nee  nuper  a  Belgis  prodiit,  sed  tot  iam  annis  antea 
proditum  a  lo.  Baptista  Porta,  Magiae  naturalis  libro  XVII,  Cap.  X,  De  Crystal- 
linae  lentis  affectibus.  Utque  appareat,  ne  compositionem  quidem  cavae  et  con- 
vexae  lentis  esse  novam,  age  verba  Portae  producamus.  Sic  ille  : 

' '  Posito  oculo  in  centra,  retro  lentem,  quae  remota  fuerint  adeo  propinqua  videbis,  ut 
quasi  manu  ea  tangere  videaris,  ut  valde  remotos  cognoscas  amicos :  literas  epistolae  in 
debita  distantia  collocatae,  adeo  magnas  videbis,  ut  perspicere  legas :  si  lentem  inclinabis  ut 
per  obliquum  epistolam  inspicias,  literas  satis  maiusculas  videbis,  ut  etiam  per  viginti  pas- 
sus  remotas  legas :  et  si  lentes  multiplicare  noveris,  non  vereor  quin  per  centum 
passus  minimam  literam  conspiceris,  ut  ex  una  in  alteram  maiores  reddantur  characteres. 
Debilis  visus,  ex  visus  qualitate  specillis  utatur.  Qui  id  recte  scwerit  accommodare,  non 
parvum  nanciscetur  secretum.  Concavae  lentes,  quae  longe  sunt  clarissime  cernere  faciunt, 
convexa  propinqua,  unde  ex  visus  commoditate  hisfrui  poteris.  Concavo,  longe  parva  vides, 
sed  perspicua;  convexo,  propinqua  maiora,  sed  turbida :  si  utrumque  recte  componere 
noveris,  et  longinqua  et  proxima  maiora  et  clara  videbis.  Non  parum  multis  amicis 
auxilii  praestitimus,  qui  et  longinqua  obsoleta,  proxima  turbida  conspiciebant,  ut  omnia 
perfectissimo  contuerentur.  Haec  Capite  X."  Etc. 


250  NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 

"  There  are  to  be  seen  there  in  Chapter  V,  where  I  demonstrate  what  pertains 
to  the  manner  of  seeing,  on  fol.  202,  representations  of  a  concave  and  convex  lens 
united  in  a  diagram,  plainly  in  the  same  way  that  they  are  customarily  joined 
together  to-day  in  the  common  tubes  [telescopes].  If  the  reading  of  Porta's 
Magic  did  not  give  occasion  to  this  contrivance,  or  if  some  Dutchman  with  in- 
struction from  Porta  himself  did  not,  when  the  injunctions  of  silence  had  been 
dissolved  by  the  death  of  Porta,  multiply  the  manufactured  instrument  to  numer- 
ous specimens,  in  order  to  make  merchandise  for  sale,  certainly  this  very  figure  at 
folio  202  of  my  book  could  suggest  the  construction  to  a  curious  reader,  especially 
if  he  joined  the  reading  of  my  demonstrations  with  Porta's  text. 

"Still,  it  is  not  incredible  that  clever  gravers  among  an  industrious  people, 
who  use  lenses  for  looking  at  the  minute  details  of  engraving,  should  by  chance, 
too,  fall  upon  this  device,  in  variously  associating  convex  lenses  with  concave,  in 
order  to  select  the  combination  that  best  suits  their  eyes. 

"  I  do  not  say  that  to  lessen  the  praise  of  the  inventor,  whoever  he  was.  I 
know  how  great  the  difference  is  between  theoretical  conjectures  and  ocular  ex- 
perience ;  between  Ptolemy's  discussion  about  the  Antipodes  and  Columbus' s  dis- 
covery of  the  new  world  :  so,  too,  between  the  commonly  circulated  two-lensed 
tubes  and,  Galileo,  your  contrivance,  with  which  you  have  bored  through  the 
very  sky  :  but  I  am  striving  here  to  create  for  the  incredulous  a  belief  in  your 
instrument. 

"  Confession  should  be  made,  that  at  the  time  I  attacked  the  Optics,  when  the 
Emperor  repeatedly  asked  me  about  the  above-written  artifices  of  Porta's,  I  der- 
ogated faith  in  them  as  much  as  possible.  Nor  is  it  wonderful :  for  he  manifestly 
mixes  incredible  things  with  probable  ones ;  and  the  title  of  Chapter  XI,  with 
the  words  To  look  forth  extremely  far,  beyond  all  thought,  seemed  to  involve  an  optical 
absurdity  :  as  if  vision  were  made  by  emission,  and  lenses  sharpened  the  rays  of 
the  eye,  so  that  they  could  penetrate  more  remotely  than  if  no  lenses  were  used  : 
or  if,  as  Porta  acknowledges,  vision  were  made  by  receiving ;  as  if  then  the 
glasses  conciliated  or  increased  the  light  for  seeing  things  :  while  this  rather  was 
true,  those  things  that  did  not  send  any  light  far  enough  to  reach  our  eyes  and  so 
be  seen  would  never  be  detected  by  any  glass. 

"  Besides,  I  not  only  believed  that  the  air  was  thick  and  of  a  blue  color,  so  as 
at  a  distance  to  cover  up  and  confuse  the  minute  parts  of  visible  things ;  and,  as 
that  was  certain,  I  saw  it  was  vain  to  expect  from  a  spyglass  that  it  should  strip 
off  this  substance  of  the  intermediate  air  from  visible  objects;  but  also,  in  re- 
gard to  the  celestial  essence  itself,  I  suspected  it  was  such  a  thing  that  it  could 
hinder  us,  if  we  should  very  greatly  increase  the  body  of  the  moon  into  some- 
thing immense,  from  being  able  so  well  to  recognize  the  small  particles  of 
the  moon  in  their  purity  apart  from  the  extremely  deep  celestial  matter. 

"For  those  reasons,  then,  I  abstained  from  undertaking  any  contrivance,  and 
besides  there  were  other  things  that  hindered. 

"But  now,  as  you  deserve,  most  accomplished  Galileo,  I  commend  your  ac- 
tivity ;  for  you,  setting  aside  all  mistrust,  have  applied  yourself  to  direct  ocular 
experiments ;  and  now  that  the  Sun  of  truth  has  by  means  of  your  discoveries 
risen,  you  have  dispelled  all  those  hobgoblins  of  waverings  along  with  the  night 
their  mother  ;  and  have  shown  by  deeds  what  could  be  done." 

It  may  be  overboldness  to  undertake  to  question  Kepler's 
interpretation  of  Porta's  words ;  but  it  does  clearly  appear  that 
he  misunderstood  Porta's  application  of  the  word  componere. 


NOTES    ON    MINE-SURVEYING   INSTRUMENTS.  251 

Even  Homer  sometimes  nods.  Porta  is  speaking  throughout 
only  of  the  use  of  simple  lenses,  or  spectacle-glasses,  concave 
and  convex,  and  their  use  for  near  and  far  sight,  with  perhaps 
some  exaggeration ;  and  when  he  says  "  si  utrwnque  recte  com- 
ponere  noveris"  he  means :  if  you  know  how  to  put  together,  or 
join,  or  arrange  each  kind,  not  (as  Kepler  imagines)  with  the 
other  kind,  but  with  its  appropriate  defect  of  vision  ;  a  suitable 
concave  lens  with  short  sight  and  a  proper  convex  lens  with 
far  sight.  That  understanding  is  corroborated  by  what  he  im- 
mediately goes  on  to  say,  of  aiding  many  nearsighted  and  far- 
sighted  friends,  so  that  they  saw  both  distant  and  near  things 
distinctly.  Obviously,  each  friend  could  have  had  only  one 
of  the  two  defects  of  sight,  nearsightedness  or  farsightedness, 
and  so  must  have  used  only  one  kind  of  lens  for  it.  Porta  at 
first  certainly  speaks  of  the  use  of  a  single  lens,  and  when  he 
mentions,  perhaps  only  hypothetically,  the  greater  effect  from 
multiplying  lenses,  he  seems  to  mean  increasing  the  number 
of  lenses  of  one  kind,  with  power  thereby  enhanced.  All  the 
rest  appears  to  be  about  single  lenses  or  spectacle-glasses. 

Kepler's  citations  from  Porta,  however,  apparently  convinced 
both  the  friends  and  opponents  of  Galileo  at  that  time  that 
Porta,  and  not  the  Dutchman,  had  been  the  first  inventor  of  the 
telescope ;  and  the  accounts  of  Porta  down  to  the  present  day 
seem  to  be  based  simply  upon  Kepler.  Even  Grant  and  more 
clearly  the  Encyclopaedia  Britannica  quote  Porta  as  speaking  dis- 
tinctly of  joining  together  concave  and  convex  glasses ;  whereas 
his  words,  as  we  have  seen,  do  not  by  any  means  justify  that 
interpretation,  though  Kepler  may  be  excusable  for  so  misun- 
derstanding them  at  the  subsequent  first  announcement  of  the 
refracting  telescope. 

That  Porta  was  not  incapable  of  exaggeration  is  now  evident 
from  a  citation  that  Franciscus  Sitius,  a  contemptuous  opponent 
of  Galileo,  makes  from  Porta's  book,  arguing  the  obvious  ab- 
surdity of  the  idea  that  such  a  man  as  Galileo  should  discover 
what  the  great  Ptolemy  with  equal  opportunity  had  not  seen. 
The  passage  occurs  in  Sitius's  essay  printed  with  Galileo's 
works,  Florence  edition,  1892,  p.  238.  Porta  there  tells  how 
Ptolemy  had  a  spyglass  that  enabled  him  on  the  Pharos  tower 
at  Alexandria  to  see  a  ship  at  sea  500  stadia  off  (about  60  miles 
— not  600,  as  Smith  has  it).  The  curvature  of  the  earth's  sur- 


252  NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 

face  would  alone  require  the  tower  to  be  about  2000  feet  high 
to  see  a  ship  sixty  miles  off.  Hence  it  is  equally  plain  that  not 
only  were  the  inventors  of  the  telescope  forestalled  by  nearly 
2000  years,  but  Eiffel  himself  was  immensely  outdone. 

Furthermore,  it  is  now  perfectly  plain  from  the  European 
experience  at  the  time  of  the  Dutch  invention,  scarcely  fifty 
years  later  than  Porta,  that  a  refracting  telescope  used  by  many 
friends,  and  evidently  made  no  secret,  would  not  have  escaped 
rapid  transmission  through  Europe.  Beyond  question,  then, 
Porta  knew  absolutely  nothing  of  the  telescope. 

Digges. — The  next  supposed,  and  really  much  more  circum- 
stantial mention  of  the  telescope  is  in  the  book  published  in 
1571  under  the  title:  A  Geometrical  Practise  named  Pantom.etria 
.  .  .  framed  by  Leonard  Digges  Gentleman,  lately  finished  by 
Thomas  Digges  his  sonne.  There  is  a  copy  of  the  book  in  the 
Philadelphia  Library.  The  book  is  7J  inches  by  5J  and  f 
inch  thick  besides  the  leather  covers.  It  is  unpaged,  and 
printed  mostly  in  black  letter,  with  interspersed  italics  and 
letters  like  our  modern  so-qalled  antique  letters.  There  are  a 
number  of  illustrations.  At  the  end  of  the  volume  the  son 
speaks  of  himself  as  in  his  twenty-fifth  year.  The  father  is 
supposed  to  have  died  about  1570.  An  epistle  dedicating  the 
work  to  "  Sir  Nicolas  Bacon,  Knight,  Lord  keper  of  the  great 
seale  of  England,"  speaks  of  the  father's  "  untimely  death  " 
and  of  the  book  as  one  of  "  certaine  volumes  that  he  in  his 
youthe  time  long  sithens  had  compiled  in  the  English  tongue." 
The  preface  among  other  things  says  : 

"Archimedes  also  (as  some  suppose)  with  a  glasse  framed  by  revolution  of  a 
section  Parabolicall,  fired  the  Romane  nauie  in  the  sea  comming  to  the  siege  of 
Syracusa.  But  to  leave  these  celestiall  causes  and  things  doone  of  antiquitie  long 
ago,  my  father  by  his  continual  paynfull  practises,  assisted  with  demonstrations 
Mathematical!  was  able,  and  sundrie  times  hath  by  proportionall  Glasses  duely 
situate  in  conuenient  angles,  not  only  discouered  things  farre  off,  read  letters, 
numbered  peeces  of  money  with  the  very  coyne  and  superscription  thereof,  cast 
by  some  of  his  freends  of  purpose  vppon  Downes  in  open  fieldes,  but  also  seuen 
myles  of  declared  what  hath  been  doon  at  that  instante  in  priuate  places  :  He 
hath  also  sundrie  times  by  the  Sunne  beames  fired  Powder,  and  dischargde  Ordi- 
nance half  a  mile  and  more  distante,  whiche  things  I  am  the  boulder  to  reporte, 
for  that  there  are  yet  liuing  diuerse  (of  these  his  doings)  Oculati  testes,  and  many 
other  matters  farre  more  straunge  and  rare  which  I  omitte  as  impertinente  to  this 
place." 

Evidently  Archimedes's  "  glasse "  was  a  mirror ;    and  the 


NOTES    ON    MINE-SURVEYING   INSTRUMENTS.  253 

word  "  glasse  "  is  used  in  the  same  way  in  the  21st  Chapter, 
where  it  is  described 

' '  How  ye  may  most  pleasantly  and  exactly  with  a  playne  glasse  from  an  highe 
cliffe,  measure  the  distance  of  any  shippe  or  shippes  on  the  sea  as  followeth.  The 
best  kinde  of  glasse  for  this  purpose  is  of  steele  finely  pullished,  so  that  the  Super- 
ficies thereof  be  smoothe,  neyther  convexe  nor  concave,  but  flatte  and  playne  as 
may  be  possible,"  etc. 

At  the  end  of  the  same  21st  Chapter  is  the  principal  account 
of  what  has  been  taken  to  be  the  telescope.  The  whole  passage 
is  as  follows,  and  in  it  the  same  use  of  the  word  "  glasse  "  for 
mirror,  and  of  the  word  "  playne  "  in  distinction  from  con- 
vex and  concave  is  to  be  observed : 

"  Thus  muche  I  thought  good  to  open  concerning  the  effects  of  a  playne  Glasse, 
very  pleasant  to  practise,  yea  most  exactlye  seruing  for  the  description  of  a  playne 
champion  countrey.  But  marvey louse  are  the  conclusions  that  may  be  perfourmed 
by  glasses  concave  and  convex  of  circulare  and  parabolicall  fourmes,  vsing  for 
multiplication  of  beames  sometime  the  ayde  of  glasses  transparent,  whiche  by 
fraction  should  vnite  or  dissipate  the  images  or  figures  presented  by  the  reflection 
of  other.  By  these  kinde  of  glasses  or  rather  frames  of  them,  placed  in  due 
angles,  ye  may  not  onely  set  out  the  proportion  of  an  whole  region,  yea  represent 
before  your  eye  the  liuely  ymage  of  euery  towne,  village,  &c.,  and  that  in  as  little 
or  great  space  or  place  as  ye  will  prescribe,  but  also  augment  and  dilate  any  parcell 
thereof,  so  that  whereas  at  the  firste  apparance  an  whole  towne  shall  present 
it  selfe  so  small  and  compacte  together  that  ye  shall  not  discerne  any  difference  of 
streates,  ye  may  by  apply  cation  of  glasses  in  due  proportion  cause  any  peculiare 
house,  or  roume  thereof  dilate  and  shew  it  self  in  as  ample  fourme  as  the  whole 
towne  firste  appeared,  so  that  ye  shall  discerne  any  trifle,  or  reade  any  letter  lying 
there  open,  especially  if  the  sonne  beames  may  come  vnto  it,  as  playnly  as  if  you  wer 
corporally  present,  although  it  be  distante  from  you  as  farre  as  eye  can  discrye  : 
But  of  these  conclusions  I  minde  not  here  more  to  intreate,  hauing  at  large  in  a 
volume  by  it  selfe  opened  the  miraculous  effectes  of  perspectiue  glasses.  And  that 
not  onely  in  matters  of  discouerie,  but  also  by  the  sunne  beames  to  fire,  pouder,  or 
any  other  combustible  matter,  whiche  Archimedes  is  recorded  to  haue  done  at  Syra- 
cusa  in  Sicilie,  when  the  Roinane  Nauy  approched  that  Towne.  Some  haue  fondly 
surmised  he  did  it  with  a  portion  of  a  section  Parabolical  artificially  made  to  reflect 
and  vnite  the  sonne  beames  a  great  distance  of,  and  for  the  construction  of  this 
glasse  take  great  paynes  with  highe  curiositie  to  write  large  and  many  intricate  de- 
monstrations, but  it  is  a  meere  fansie  and  vtterly  impossible,  with  any  one  glasse 
whatsoeuer  it  be  to  fire  any  thing,  onely  one  thousand  pase  off,  no  though  it  were 
a  100  foote  over,  marry  true  it  is,  the  Parabola  for  his  small  distance,  most  per- 
fectly doth  vnite  beames,  and  most  vehemently  burneth  of  all  other  reflecting 
glasses.  But  how  by  application  of  mo  glasses  to  extende  this  vnitie  or  concourse 
of  beames  in  his  full  force,  yea  to  augment  and  multiply  the  same,  that  the 
farder  it  is  caried  the  more  violently  it  shall  pearse  and  burne.  Hoc  opus  hie 
labor  est,  wherein  God  sparing  lyfe,  and  the  tyme  with  opportunitie  seruing,  I 
minde  to  imparte  with  my  countrey  men  some  such  secretes,  as  hath  I  suppose  in 
this  our  age  ben  revealed  to  very  fewe,  no  lesse  seruing  for  the  securitie  and  de- 
fence of  our  naturall  countrey,  than  surely  to  be  mervailed  at  of  straungers." 


254  NOTES    ON    MINE-SURVEYING    INSTRUMENTS. 

It  is  evident  that  he  writes  of  a  reflecting  telescope,  and  not 
of  a  refracting  one.  The  "  ayde  of  glasses  transparent "  there- 
with is  mentioned  as  only  "  sometime  useful,"  apparently  for 
the  eye-piece,  or,  as  he  says,  for  "  multiplication  of  beanies," 
because,  merely,  the  "  fraction  should  unite  or  dissipate  the 
images  or  figures  presented  by  the  reflection  of  the  other " 
glass,  or  mirror — that  is,  cause  the  rays  to  converge  or 
diverge. 

One  difficulty  in  believing  that  a  telescope  existed  in  England 
before  1571,  nearly  forty  years  before  the  first  Dutch  telescope, 
has  been  to  account  for  its  not  becoming  in  all  that  time  widely 
known  and  used,  whereas  the  fame  and  use  of  the  Dutch  tele- 
scopes ran  through  all  Europe  within  a  few  months.  The  rea- 
son may  well  be  that  Digges's  telescope  was  a  reflecting  one, 
comparatively  difficult  and  costly  of  construction.  Even  in 
Friar  Bacon's  time,  in  the  depth  of  the  dark  ages,  a  refracting 
telescope  really  in  use  could  hardly  fail  to  have  been  copied,  as 
the  spectacle-glasses  were,  and  to  have  spread  through  Europe. 
The  last  sentence  of  Digges's  account  seems  also  to  intimate 
that  the  value  of  even  a  reflecting  telescope  for  military  pur- 
poses was  fully  appreciated,  or  perhaps  over-estimated,  and  that 
consequently  its  use  had  "  ben  revealed  to  very  fewe,  no  lesse 
seruing  for  the  securitie  and  defence  of  our  naturall  countrey, 
than  surely  to  be  mervailed  at  of  straungers."  Digges  appears 
to  have  had  the  friendship  of  very  high  officials,  and  the  dedi- 
catory epistle  to  Queen  Elizabeth's  celebrated  Lord  Keeper 
of  the  Great  Seal,  Sir  Nicholas  Bacon,  father  of  the  famous 
Lord  Bacon,  mentions  "  the  great  fauour  your  lordship  bare  my 
father  in  his  lifetime  and  the  conference  it  pleased  your  honor 
to  vse  with  him."  It  is  not  impossible  that  the  government 
may  have  discouraged  the  general  promulgation  of  the  method 
of  constructing  the  telescope ;  just  as  the  first  idea  in  regard  to 
the  Dutch  telescope  was  to  keep  it  secret  for  military  uses.  At 
any  rate,  the  younger  Digges  in  his  several  later  books  never 
published  the  full  description  of  the  telescope,  according  to 
what  he  says  of  "  having  at  large  in  a  volume  by  it  selfe  opened 
the  miraculous  effectes  of  perspectiue  glasses."  The  word 
"  perspective  "  here  does  not  appear  to  imply  transparency,  but 
to  be  used  rather  in  place  of  "  prospective  "  or  "  optical." 

In  his  book  called  Stratioticos,  published  in  1579,  is  said  to 


NOTES    ON    MINE-SURVEYING   INSTRUMENTS.  255 

occur,  at  p.  359,  the  statement  that  his  father,  "  among  other 
curious  practices  had  a  method  of  discovering  by  perspective 
glasses  set  at  due  angles  all  objects  pretty  far  distant  that  the 
sun  shone  upon,  which  lay  in  the  Country  round  about,"  and 
that  this  was  by  the  help  of  a  manuscript  book  of  Roger  Bacon 
of  Oxford.  The  repeated  mention  of  the  "  due  angles  "  at 
which  the  glasses  must  be  set  seems  to  indicate  the  necessary 
observance  of  the  angles  of  incidence  and  reflection  of  mirrors, 
and  to  be  quite  inapplicable  to  the  description  of  the  refracting 
telescope. 

We  may  then  safely  conclude  that  Leonard  Digges  did  really 
use  a  reflecting  telescope ;  but  that  the  refracting  telescope  was 
not  yet  invented. 

Lippershey. — The  next  telescope  was  the  Dutch  refracting 
telescope  of  1608.  Its  origin  was  fully  set  forth  so  long  ago  as 
1831,  in  Vol.  I.  of  the  Journal  of  the  Royal  Institution,  by  Dr. 
G.  Moll,  of  Utrecht,  in  his  account  of  the  already  deceased 
Professor  Van  Swinden's  researches  into  the  government  ar- 
chives at  the  Hague.  They  fully  established  the  fact  that  the 
spectacle  maker,  Hans  Lippershey,  of  Middelburg,  was  the 
maker  of  the  first  refracting  telescope,  previous  to  Oct.  2, 1608 
(in  the  midst  of  the  80  years'  war) ;  for  the  government  on 
that  day  considered  his  petition  for  a  patent  on  the  instrument, 
or  an  annual  pension,  in  case  the  government  should  require  the 
exclusive  use  of  the  invention.  Less  accurate  investigations  in 
1655  gave  the  credit  to  another  spectacle-maker  named  Zacha- 
rias  Jansen,  in  1610 ;  who,  according  to  those  investigations, 
would  appear  to  have  invented  the  compound  microscope  about 
1590 ;  though  Fontana  claims  to  have  invented  it  in  1618,  and 
Huygens's  investigations  make  it  probable  that  it  was  first  in- 
vented by  Drebel,  a  Dutchman,  in  London,  about  1620.  Jacob 
Adrianzoon,  a  learned  mathematician,  also  called  James  Metius 
(called  Metius  from  a  student-nickname  that  clung  to  a  brother 
of  his  through  life),  applied  to  the  government  on  October  17, 
1608,  for  a  patent  on  a  telescope  of  his  invention  as  powerful  as 
the  one  lately  offered  to  the  government  by  a  spectacle-maker  of 
Middelburg — that  is,  evidently  by  Lippershey.  Adrianzoon 
claimed  to  have  made  his  discovery  independently,  partly  by 
theory  and  partly  by  accident,  within  the  previous  two  years. 
He  was  not  encouraged  by  the  government,  and,  apparently  in 


256  NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 

disgust,  he  never  made  his  method  public.  The  government, 
oddly  enough,  was  not  at  first  fully  appreciative  of  Lippershey's 
wonderful,  epoch-making  discovery,  or  at  least  not  satisfied;  and, 
on  October  6,  1608,  required  of  him  a  spy-glass  made  of  rock- 
crystal  that  could  be  used  with  both  eyes,  at  the  price  of  300 
florins,  instead  of  the  1000  florins  he  had  at  first  demanded; 
and  exacted  a  promise  from  him  to  make  no  such  instruments 
without  the  consent  of  the  States.  He  accordingly  supplied 
them  with  such  a  binocular  on  the  15th  of  the  next  December; 
and  they  ordered  two  more  like  it,  and  paid  him  900  florins, 
or  about  $360,  for  the  three  (not  for  one,  as  some  say) ;  but 
they  refused  the  patent,  because  the  invention  had  already  be- 
come known  to  many. 

Lippershey's  first  discovery  happened  by  accident,  as  the 
common  story  goes  ;  that  is,  he  had  the  intelligence  to  perceive 
the  bearings  of  an  accidental  observation.  It  is  said  that  he 
chanced  to  look  through  two  spectacle  lenses,  one  in  each  hand, 
towards  a  neighboring  steeple,  and  was  astonished  to  find  how 
near  and  distinct  the  weathercock  became.  It  has  been  urged 
against  the  story  that  it  also  mentions  that  the  weathercock  be- 
came inverted,  as  it  would  be  if  seen  through  two  convex  lenses ; 
whereas  the  Dutch  telescope  was  not  inverting,  but  was  made 
with  a  convex  and  a  concave  lens.  It  is,  however,  more  prob- 
able that  the  two  lenses  in  his  hands  should  be  alike,  and  not 
in  the  least  improbable  that  they  should  both  be  convex.  In- 
deed, the  effect  of  two  concave  lenses  would  scarcely  be  par- 
ticularly noticeable,  as  being  merely  of  double  the  power  and 
suited  to  doubly  nearsighted  eyes.  It  is  the  remarkable  dif- 
ference in  the  effect  of  two  convex  lenses  at  an  accidentally 
suitable  distance  apart  that  would  have  been  especially  strik- 
ing. He  evidently  was  a  very  intelligent,  ingenious  man,  and 
doubtless  was  as  ready,  either  by  theoretical  or  by  experimental 
investigations,  to  obviate  the  inconvenience  of  the  inversion  as 
he  later  was  to  prepare  a  binocular  for  the  exacting  legislators. 
The  inverting  telescope  accordingly  remained  in  abeyance  until 
Kepler  suggested  its  advantages  in  1611,  and  Scheiner  con- 
structed one  in  1617,  and  published  it  in  1630. 

Lippershey's  first  telescope  was,  on  the  2d  of  October,  1608, 
in  the  possession  of  Maurice,  Prince  of  Orange  and  Count  of 
Nassau,  the  head  of  the  Dutch  government.  At  first  it  was 


NOTES    ON    MINE-SURVEYING   INSTRUMENTS.  257 

thought  to  keep  the  invention  secret  for  military  purposes ;  but 
it  soon  got  abroad,  and  within  a  few  months  its  fame  (mainly 
as  a  curious  toy,  to  be  sure)  had  gone  all  over  Europe. 

Galileo. — The  account  of  Galileo's  reinvention  of  the  tele- 
scope, as  related  by  Moll  from  Galileo's  own  writings,  and 
essentially  repeated  by  Grant  and  other  writers,  shows  they 
had  never  seen  one  or  two  letters  of  Galileo  that  were  not 
published  until  1847,  and  that  throw  a  little  additional  light  on 
the  matter. 

The  date  of  the  reinvention  has  never  been  exactly  fixed,  but 
was  long  taken  to  be  in  May,  or  even  in  April,  1609 ;  owing  to 
Galileo's  first  public  mention  of  it,  in  his  Nundus  Sidereus,  pub- 
lished early  in  March,  1610,  as  having  occurred  "  nearly  ten 
months  ago  "  (mensibus  abhinc  decem  fere).  In  his  rough  draft 
he  had  written  "  eight  months,"  as  may  be  seen  in  the  fac  simile 
in  the  recent,  yet  unfinished,  Florentine  edition  of  his  works 
(1892,  vol.  iii.) ;  and  the  change  was  perhaps  due  to  delay  in 
printing,  or  to  imperfect  recollection,  or  to  a  desire  to  use  a 
round  number,  or  to  a  combination  of  more  than  one  of  these 
causes.  But  in  his  letter  of  August  29, 1609,  to  B.  Landucci, 
first  published  in  the  Florentine  edition  of  Galileo's  works,  of 
1847,  vol.  vi.,  p.  75,  he  gives  the  time  as  "  about  two  months 
ago  "  (sono  circa  a  due  mesi) ;  showing  it  clearly  to  be  not  earlier 
than  June,  1609. 

That  letter  and  the  Nundus  Sidereus  and  Galileo's  II  Saggia- 
tore,  published  in  1623,  relate  the  circumstances  in  a  sufficiently 
concordant  manner,  each  account  giving  some  points  omitted 
by  the  others.  He  says,  then,  that  about  June,  1609,  while  he 
was  professor  of  mathematics  at  Padua,  but  on  a  visit  to  Venice, 
rumors  came  that  a  spyglass  made  by  a  Dutchman  had  been 
presented  to  Count  Maurice  which  made  very  distant  things 
seem  very  near,  so  that  a  man  two  miles  off  could  be  distinctly 
seen ;  "  and  nothing  more  was  added  "  (ne  piu  fu  aggiunto).  The 
rumors  were  believed  by  some,  and  riot  by  others ;  but  in  a  few 
days  were  confirmed  by  a  letter  to  Galileo  from  a  French 
noble,  James  Badovere,  at  Paris.  On  Galileo's  return  from 
Venice  to  Padua  these  rumors  set  him  to  trying  to  think  out 
the  method  that  could  accomplish  such  results.  With  his 
knowledge  of  optics,  feeling  sure  it  could  not  be  with  a  single 
lens,  nor  with  two  similar  lenses,  he  that  same  night  concluded 


258  NOTES    ON    MINE-SURVEYING    INSTRUMENTS. 

it  must  be  with  a  convex  and  a  concave  lens.  The  next  day  he 
took  a  piece  of  leaden  pipe  and  put  two  such  lenses  into  it  and 
found  he  had  a  magnifying  power  of  three  times  linear.  The 
same  day,  he  sent  word  of  his  success  to  his  friends  at  Venice, 
with  whom  he  had  been  discussing  the  rumors  the  day  before. 
He  then  set  to  work  upon  another  more  perfect  telescope, 
with  a  magnifying  power  of  nine  times  linear;  and  six  days 
later,  in  compliance  with  the  government's  request,  he  took  it 
to  Venice,  where  it  was  seen  with  wonder  by  the  whole  senate 
and  all  the  principal  gentlemen  of  the  republic  for  more  than 
a  month  together,  much  to  his  own  fatigue.  They  climbed  up 
eagerly,  even  old  men,  more  than  once  to  the  top  of  the  highest 
towers  of  the  city,  and  descried  vessels  more  than  two  hours 
before  under  full  sail  they  became  visible  to  the  naked  eye.  At 
length,  by  the  advice  of  one  of  his  most  affectionate  patrons, 
and  seeing  how  useful  a  thing  the  telescope  would  be  on  sea  and 
land,  he  freely  made  a  present  of  it  to  the  Doge  in  full  assem- 
bly, on  the  25th  of  August,  1609.  The  telescope  was  received 
with  such  admiration,  that  Galileo's  professorship  was  made  an 
appointment  for  life,  and  his  yearly  salary  nearly  doubled, 
increased  to  1000  florins  (about  $900),  three  times  what  any 
previous  incumbent  had  received.  This  warm  appreciation 
of  the  merits  of  his  discovery  among  his  numerous  Venetian 
friends  is  of  itself  full  confirmation  of  his  otherwise  undoubted 
statement,  that  the  rumors  of  the  Dutch  telescope  had  been  a 
very  insufficient  guide  to  the  method  of  its  construction.  In 
his  II  Saggiatore  he  argues  against  the  detractions  of  one  of  his 
opponents  that,  although  he  claims  no  great  credit  for  the  dis- 
covery, yet  it  is  more  meritorious  to  work  out  by  reasoning  the 
method  of  attaining  a  result  known  to  be  possible,  than  to  hit 
upon  the  method  and  result  by  accident.  To  be  sure,  he  might 
not  have  thought  of  making  a  telescope,  had  it  not  been  for 
the  rumors  of  the  Dutch  one,  but  merely  on  the  suggestion  of 
those  rumored  results  he  worked  out  the  method  with  nobody's 
help.  He  deprecates  his  opponent's  attempt  to  take  away  the 
little  merit  there  might  be  in  his  performance. 

He  made  more  and  more  powerful  telescopes,  up  to  a  magni- 
fying power  of  not  more  than  thirty-two  or  thirty-three  times 
linear,  about  the  limit  for  telescopes  of  the  Galilean  kind  with- 
out achromatic  correction,  and  about  a  yard  in  length.  But 


NOTES    ON    MINE-SURVEYING   INSTRUMENTS.  259 

his  chief  merit  was  the  immediate  application  of  the  telescope 
to  astronomical  discoveries  that  startled  the  world,  especially 
theologians. 

IMPROVEMENTS. 

Micrometer  and  Cross-Hairs. — With  the  Keplerian  telescope 
first  came  the  possibility  of  the  micrometer,  invented  hy  Gas- 
coigne  perhaps  as  early  as  1638,  when  he  was  only  about  eighteen 
years  old ;  and  it  was  seen  hy  Crabtree  in  1639,  as  mentioned 
in  a  letter  of  his  to  Horrocks.*  Flamsteed's  Historia  Coelestis, 
Vol.  I.,  records  the  mutual  distances  of  the  Pleiades  as  given 
by  Gascoigne  to  seconds  in  a  letter  of  22  May,  1639,  to  Crab- 
tree,  distances  apparently  measured  with  the  micrometer. 
Twenty  years  later  it  was  reinvented  on  the  Continent.  The 
micrometer  had  two  straight  edges  of  metal  that  were  by  a 
screw  made  to  approach  each  other  at  the  focus  of  the  telescope. 
Hooke  suggested  using  human  hairs  instead  of  the  metallic 
edges.  Silver  wires  and  silk  fibers  were  used  in  the  early 
continental  micrometers ;  and  Mr.  Brough  points  out  that  a 
century  later  lines  on  glass  or  mica  were  used  at  the  focus. 
Spider-webs  were  not  applied  until  David  Bittenhouse's  inven- 
tion in  1785,  unless  Mr.  Brough  can  substantiate  his  date  of 
1775. f  For  in  November,  1785,  a  letter  from  Eittenhouse  was 
read  before  the  American  Philosophical  Society,  with  the  fol- 
lowing postscript  (A.  P.  S.  Trans.,  1786,  Old  Series,  Vol.  II., 
p.  183): 

"P.  S.  The  great  improvement  of  object  glasses  by  Dolland  [sic']  has  enabled 
us  to  apply  eye-glasses  of  so  short  a  focus,  that  it  is  difficult  to  find  any  substance 
proper  for  the  cross-hairs  of  fixed  instruments.  For  some  years  past  I  have 
used  a  single  filament  of  silk,  without  knowing  that  the  same  was  made  use  of 
by  the  European  astronomers,  as  I  have  lately  found  it  is  by  Mr.  Hirschell  |>'c]. 
But  this  substance,  though  far  better  than  wires  or  hairs  of  any  kind,  is  still 
much  too  coarse  for  some  observations.  A  single  filament  of  silk  will  totally 
obscure  a  small  star,  and  that  for  several  seconds  of  time,  if  the  star  be  near  the 
pole.  I  have  lately  with  no  small  difficulty  placed  the  thread  of  a  spider  in 
some  of  my  instruments  ;  it  has  a  beautiful  effect ;  it  is  not  one-tenth  of  the  size 
of  the  thread  of  the  silkworm,  and  is  rounder  and  more  evenly  of  a  thickness. 
I  have  hitherto  found  no  inconvenience  from  the  use  of  it,  and  believe  it  will 
be  lasting,  it  being  more  than  four  months  since  I  first  put  it  in  my  transit 
telescope,  and  it  continues  fully  extended  and  free  from  knobs  or  particles  of 
dust." 

*  Cited  by  Grant  (p.  452)  from  Sherburne's  translation  of  the  Sphere  of  Manil- 
ius,  1675,  p.  92.  f  Page  70. 

18 


260  NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 

This  distinct  statement  seems  to  put  at  rest  Mr.  Scott's  asser- 
tion,* apparently  taken  from  the  Encyclopaedia  Britannica  (under 
Micrometer},  that  Troughton  was  the  first  to  put  spider-webs 
to  practical  use,  on  Bittenhouse's  suggestion.  The  Encyclopaedia 
also  says  that  they  were  first  suggested,  though  not  used,  by 
Prof.  Fontana,  of  Florence,  in  1755. 

Rittenhouse' 's  First  Telescope. — Mr.  Scott  adds  that  Bittenhouse 
at  the  time  of  his  invention  was  "  constructing  the  first  Ameri- 
can telescope."  A  diligent  search  through  several  biographies 
and  notices  of  Rittenhouse  at  Philadelphia,  his  home,  and 
through  papers  in  the  Transactions  of  the  American  Philosophical 
Society,  Yols.  I.  and  II.,  has  failed  to  be  rewarded  by  the  dis- 
covery of  the  least  allusion  to  any  such  priority  of  construction 
by  him;  though  already  .at  the  time  of  the  transit  of  Venus  in 
1769  he  had  shown  himself  not  only  a  learned  theorist  but 
"  mechanic  enough  to  make  with  his  own  hands  an  equal  alti- 
tude instrument,  a  transit  telescope  and  a  timepiece."  He  ap- 
pears to  have  made  his  own  first  telescope  about  1756,  when  he 
was  twenty-four  years  old. 

Platinum  Cross- Wires. — In  1871  Messrs.  Heller  &  Brightly, 
of  Philadelphia,  introduced  and  published  the  use  of  platinum 
cross-wires  y-^Vs"  °^  an  incn  in  thickness,  or  as  thin  as  ordinary 
spiders'  webs,  in  the  telescopes  of  engineering  transits.  The 
platinum  wires  obviate  the  sagging  which  dampness  causes  in 
spiders'  webs ;  and,  not  being  transparent,  can  easily  be  seen 
when  the  sight  is  towards  a  light,  say  the  sun,  the  north  star, 
or  a  lamp.  (See  the  Report  of  the  Franklin  Institute  Com- 
mittee, December  18,  1871.) 

Telescopic  Sights. — The  possibility  of  using  a  telescope  for 
ascertaining  with  precision  the  direction  of  sight,  and  conse- 
quently the  application  of  telescopes  to  graduated  instruments, 
depend,  of  course,  on  the  use  of  two  convex  lenses,  the  Kep- 
lerian  arrangement;  for  with  the  Galilean  method  there  is  no 
means  of  marking  a  definite  and  invariable  optical  axis  of  the 
telescope.  Here,  too,  the  young  Gascoigne,  who  died  at  Marston 
Moor,  1644,  in  his  twenty-fourth  year,  was  the  leader,  and, 
already  by  1640,  he  used  for  the  purpose  a  hair  or  thread  at 
the  focus.  It  was  even  claimed  in  1675  that  he  had  been  the 

*  Page  20. 


NOTES    ON    MINE-SURVEYING    INSTRUMENTS.  261 

first  to  use  a  telescope  of  two  convex  lenses.  At  any  rate,  he 
was  evidently  the  first  to  use  telescopic  sights. 

Reflecting  Telescope. — Keplerian  telescopes,  with  two  convex 
lenses,  were  used,  then,  for  astronomical  purposes;  and  were 
made  of  enormous  length  by  Huygens,  Cassini  and  others, 
even  up  to  300  feet  long,  and  without  tubes,  and  called  there- 
fore aerial  telescopes.  But  the  spherical  aberration,  already 
understood,  and  especially  the  chromatic  aberration,  then  un- 
known, prevented  satisfactory  definition ;  and  in  1663  James 
Gregory  proposed  the  reflecting  telescope,  since  called  by  his 
name,  and  was  the  first  to  explain  completely  its  construction, 
though  the  idea  had  long  been  known  in  a  general  way.  New- 
ton, after  his  discovering  the  reason  of  chromatic  aberration, 
made  the  first  reflecting  telescope,  except,  as  we  now  have 
reason  to  believe,  Digges's  of  a  hundred  years  before.  Newton 
made  his  invention  public  in  1671. 

Achromatic  Lens. — Achromatic  lenses  were  first  made,  it 
seems,  in  1733  by  Chester  Moor  Hall,  an  English  lawyer  and 
mathematician,  but  he  was  in  independent  circumstances  and 
took  no  special  pains  to  publish  his  invention  or  get  a  patent; 
and  in  1758  John  Dollond,  of  London,  made  public  his  suc- 
cessful construction  of  an  achromatic  lens,  and  he  obtained  a 
patent  on  it.  The  patent  was  legally  maintained  notwithstand- 
ing the  earlier  invention  by  Hall,  whose  neglect  expressly  to 
publish  it  was  severely  animadverted  upon  by  the  judge. 

The  difficulty  of  making  satisfactory  flint  glass  was  still  an 
obstacle  to  the  construction  of  large  astronomical  achromatic 
lenses,  until  Guinand,  a  humble  Swiss  watchmaker,  after  seven 
years  of  experiments  succeeded  in  1790  in  producing  by  secret 
methods  large  masses  of  flint  glass  free  from  striae.  Fraun- 
hofer  induced  him  to  remove  with  the  secret  to  Munich  in 
1805.  Curiously  enough,  throughout  the  world,  producers  of 
large  disks  of  glass  trace  their  success  to  information  obtained 
more  or  less  directly  from  Guinand. 

Dr.  Blair,  whose  success  Mr.  Scott,  on  the  authority  of  the 
Rev.  Dr.  Dick,  cites  with  approval,*  contrived  (Edin.  Trans., 
Vol.  III.,  p.  53)  a  partly  fluid  achromatic  object  glass,  with 
hydrochloric  acid  filling  the  space  between  the  convex  sur- 

*  Page  19. 


262  NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 

faces  of  a  meniscus  and  a  plano-convex  lens ;  but,  as  pointed  out 
in  the  Encyclopaedia  Britannica  (under  Telescope,  p.  143),  such 
combinations  are  practically  useless,  not  only  from  unavoidable 
leakage,  but  also  because  in  fluid  lenses  changes  of  tempera- 
ture set  up  currents  equivalent  in  effect  to  want  of  homogeneity 
in  the  flint  lens. 

Kellner  Lens  in  Erecting  Telescopes. — In  1873  the  Kellner 
achromatic  compound  lens  eye-piece  was,  by  means  of  two 
suitable  additional  lenses,  first  made  applicable  by  Heller  & 
Brightly  to  the  erecting  telescopes  that  American  engineers 
commonly  prefer.  The  result  is  excellent  definition  from  the 
completeness  of  the  achromatism,  greatly  increased  light  from 
the  much  enlarged  opening  of  the  diaphragm  between  the 
object  lens  of  the  eye-piece  and  the  accumulative  lens,  and  at 
the  same  time  the  spherical  aberration  is  so  completely  over- 
come as  to  leave  the  field  flat,  and  make  stadia  measurements 
very  much  more  satisfactory. 

Inverting  Telescope. — In  spite  of  the  better  magnifying  power, 
better  definition,  better  light  and  larger  field  of  the  inverting 
telescope  for  the  same  size  and  weight  of  telescope,  and  not- 
withstanding the  remarkable  ease  of  accustoming  one's  self  to 
the  inversion,  American  engineers  generally  demand  that  the 
telescope  shall  not  invert.  It  seems  to  be  a  wholly  unaccount- 
able prejudice,  considering  the  instrument's  greatly  increased 
lightness  and  convenience  obtained  with  an  inverting  telescope 
of  equal  precision. 

IV.  THEODOLITE. 

Origin. — The  evident  origin  of  the  theodolite  has  been 
strangely  overlooked  by  Mr.  Scott,  Mr.  Hoskold  and  others  in 
their  examination  of  Digges's  Pantometria.  Obviously,  not  his 
theodelitus,  but  his  "  Topographicall  instrument "  is  essentially 
the  modern  theodolite,  with  the  yet  unknown  refracting  tele- 
scope replaced  by  sights,  and  with  the  support  for  them  and 
for  the  vertical  semicircle  reduced  to  a  mere  central  pillar. 
His  29th  chapter  describes  the  instrument  as  follows : 

"  The  Construction  of  an  instrument  Topographicall  seruing  most  commodiously 
for  all  manner  mensurations. 

"  Having  alreadie  plainly  declared  the  making  of  the  Quadrant  Geometricall 
with  his  scale  therein  contayned,  whose  vse  is  chiefly  for  altitudes  and  profundi- 
ties :  the  composition  also  of  the  square  and  planisphere  or  circle  named  Theo- 


NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 


263 


delitus  for  measuring  lengthes  breadthes  and  distances.  Yt  may  seeme  superfluous 
more  to  write  of  these  matters,  yet  to  finishe  this  treatise,  I  thinke  it  not  amisse 
to  shew  how  you  may  ioyne  these  three  in  one,  whereby  you  shall  frame  an  instru- 
ment of  such  perfection,  that  no  maner  altitude,  latitude,  longitude,  or  profun- 
ditie  can  offer  it  selfe,  howsoeuer  it  be  situate,  which  you  may  not  both  readely 
and  most  exactly  measure.  You  shall  therefore  first  prepare  some  large  foure 
square  pullished  plate  of  Latin,  wherein  you  may  describe  your  Geometrical 
square,  his  sides  divided  in  1200  parts  at  the  left,  with  index  and  sightes  as  was 
before  shewed  :  describing  also  within  the  same  square  the  Planisphere  or  circle 
called  Theodelitus,  then  must  you  vppon  an  other  fine  pullished  plate,  drawe  your 
Quadrant,  or  rather  a  semicircle  diuided  iustly  into  180  grades,  and  within  the 

FIG.  152. 


Digges's  Square  Geometricall,  Index,  Theodelitus  and  Alhidada. 

same  a  double  scale  :  every  side  contayning  at  the  leste  an  120  partes,  finally, 
fixing  on  the  dimetient  thereof  two  sightes  perpendicularly  reared,  and  equedis- 
tantly  persed,  so  as  the  line  visuall  may  pass  parallele  to  that  diameter.  You 
haue  a  double  Quadrant  Geometricall  with  a  double  scale,  whiche  you  muste  by 
the  ayde  of  some  skilfull  Artificer,  so  place  over  the  other  plate  wherein  youre 
square  Geometricall  and  Theodelitus  was  described,  that  his  centre  maye  exactly 
reste  in  a  Perpendicular  line  from  the  centre  of  the  planisphere  or  circle  named 
Theodelitus,  his  circuference  depending  dounwarde.  And  this  double  Quadrant 
or  semicircle,  must  in  such  sorte  be  connexed  to  the  Perpendiculare  erected  from 
the  centre  of  the  planisphere,  and  alhidada  at  the  foote  thereof,  that  what  way 
so  euer  the  Diameter  with  sightes  be  turned,  the  Alhidada  maye  alway  remayne 
exactly  underneath  it,  directing  bothe  to  one  verticall  circle  or  pointe  of  the 


264 


NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 


Horizon  :  this  perpendiculare  wherevnto  the  semicircle's  centre  is  fastened,  ought 
also  to  be  marked  with  200  partes  equall  to  the  diuisions  of  the  scale  beginning  at 
the  centre,  so  proceeding  dounward  til  you  come  to  the  end  of  those  200  portions  : 
more  I  neede  not  say  of  this  instrument,  considering  the  construction,  if  every 
parte  hath  ben  seuerally  declared  sufficiently  before,  for  the  placing  and  conioyn- 
ing  them,  behold  the  Figures  [Figs.  152  and  153]. 

"  I  K  L  H  the  square  Geometrical!,  M  N  his  index  with  sightes,  G  E  F  O  Theo- 
delitus,  G  F  his  Alhidada  or  index  with  sightes  A  B  the  line  perpendiculare  from 
B  dounward  noted  with  200  partes,  equall  to  the  diuisions  of  the  scale,  DEC 
the  semicircle  hauing  on  his  Diameter  two  sightes  fixed  as  was  to  fore  declared. 
This  is  also  to  be  noted,  that  the  double  scale  is  compound  of  two  Geometricall 
squares,  the  one  seruing  for  altitudes,  the  other  for  profundities.  The  square 
which  the  line  perpendicular  cutteth  when  the  Diameter  is  directed  to  any  markes 
lying  lower  than  your  station,  I  call  the  scale  of  profundities,  the  other  shall  for 

FIG.  153. 


Digges's  Semicircle. 

distinction  be  named  the  scale  of  altitudes.  This  semicircle  ought  so  to  be 
placed  that  the  centre  B  hang  directly  over  the  centre  A,  and  that  the  diameter 
D  C  with  his  sightes  may  be  moued  vp  and  downe,  and  also  sidewise  whither  you 
list,  alwayes  carying  G  F  about  directly  under  it.  You  must  also  prepare  a  staffe 
pyked  at  the  ende,  to  pitche  on  the  ground  with  a  flat  plate  on  the  toppe  to  set 
this  instrument  vpon.  It  is  also  requisite  that  within  Theodelitus  you  haue  a 
needle  or  fly  so  rectified,  that  being  brought  to  his  due  place  the  crosse  diameters 
of  the  Planisphere  may  demonstrate  the  foure  principall  quarters  of  the  Horizon, 
East,  Weste,  North  and  Southe :  And  this  may  you  do  by  drawing  a  right  line 
making  an  angle  (with  that  one  diameter  of  youre  instrument  representing  the 
meridiane)  equal!  to  the  variation  of  the  copasse  in  your  region  :  which  in  Eng- 
land is  11 J  grades  or  neere  therabout,  and  may  be  redely  observed  in  all  places 
sundrie  wayes.  But  thereof  I  mind  not  here  to  entreate,  forasmuch  as  it  apper- 
tayneth  to  Cosmographie  &  navigatio,  whereof  I  haue  copiled  a  treatise  by  itself, 
touching  the  fabricatio  this  may  suffise." 


NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 


265 


His  30th  chapter  begins  : 


"By  this  instrument  to  knowe  how  many  myles  or  pase  any  shippe  is  distante  from  you, 
your  selfe  standing  vpon  an  highe  cliffe  or  platforme  by  the  sea  coaste. 

"Your  Topographicall  instrument  equedistantly  situate  to  the  Horizon,  (as  was 
before  declared)  turne  the  diameter  of  the  semicircle  towards  the  ship,"  etc. 

It  is  perfectly  clear  from  the  figure  (Fig.  154),  as  well  as  the 
text,  that  the  instrument  is  nothing  but  the  modern  theodolite; 
except  that  it  is  rudely  made,  and  that  it  has  sights  for  the 

FIG.  154. 


Digges's  Topographicall  Instrument  in  Use. 

naked  eye  in  place  of  the  refracting  telescope  not  then  invented. 
The  vertical  semicircle  is  joined  to  the  sights  just  as  it  is  in 
the  modern  theodolite  to  the  telescope,  but  is  supported  by  a 
pillar  from  the  center  of  the  horizontal  plate,  instead  of  by 
two  standards  or  vees;  and  the  pillar  is  joined  to  the  alidade 
instead  of  to  a  vernier  plate.  To  see  the  essential  identity,  it 
is  only  necessary  to  compare  the  figure  with  Figs.  16  and  17, 
pp.  696  and  698,  vol.  xxviii.  of  the  Transactions.  To  be  sure, 
the  "  square  geometricall "  has  been  disused  in  the  modern 
form,  and  the  graduated  plate  is  round. 


266  NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 

Digges  expressly  mentions  the  application  of  his  instrument 
to  underground  use,  meaning  particularly  military  mines,  at 
the  end  of  the  35th  chapter  and  of  the  "  fyrst  Booke,"  as  fol- 
lows : 

"A  Note  for  Mines. 

"  Most  commodiously  also  serueth  this  instrument  to  conducte  Mynes  vnderthe 
earth,  for  noting  the  Angles  of  position  in  the  Planisphere  or  Theodelitus,  and 
also  Angles  of  Altitude  or  profunditie  in  the  semicircle  or  scales  appropriate 
there vnto,  measuring  the  distances  from  Angle  to  Angle,  you  may  make  by  the 
former  preceptes  most  certeine  plattes  of  your  iorneis,  and  thereby  always  knowe 
vnder  what  place  you  are,  and  which  way  to  directe  your  Myne  to  approche  any 
other  place  you  liste." 

Derivation  of  the  Name. — The  derivation  of  the  word  theodo- 
lite has  been  variously  explained,  and  generally  quite  ludic- 
rously; for  it  has  been  a  sore  puzzle  to  philologists.  Its 
first  part  has  been  imagined  to  come  perhaps  from  Greek  words 
meaning  "to  see  a  road"  or  to  "  run  a  road;"  in  either  case 
requiring  an  o  after  the  d,  as  in  the  ordinary  modern  spelling. 
But  it  is  very  noticeable  that  Digges,  the  first  user,  and  appar- 
ently the  inventor  of  the  word,  invariably  spells  it  theodelitus, 
notwithstanding  his  extremely  varied  irregularity  in  the  spelling 
of  most  other  words.  Now  Mr.  Scott  brings  to  notice  Stanley's 
and  Bauernfeind's  two  other  derivations,  both  as  amusing  as  the 
old  explanations,  but  not  requiring  either  the  o  or  the  e,  nor 
indeed  hardly  any  of  the  other  letters.  It  seems  inconceivable 
that  anybody  could  have  formed  the  name  of  such  an  instru- 
ment from  Stanley's  theodicaea,  divine  right,  aside  from  the  lack 
of  resemblance  in  form ;  or,  according  to  Bauernfeind,  have 
corrupted  into  theodelitus  such  familiar  words  as  "  the  alidade," 
or,  as  Digges  himself  repeatedly  calls  it,  "  the  Alhidada,"  one 
part  of  his  instrument  considered  by  him  quite  distinct  from 
his  theodelitus.  Bauernfeind,  in  objecting  to  the  derivation  of 
the  termination  lite  from  lithos,  stone,  seems  to  overlook  the  fact 
that  hundreds  of  mineralogical  names  are  so  formed  in  Eng- 
lish ;  though,  it  is  true,  not  so  long  as  300  years  ago.  But  in 
any  case,  what  in  the  world  has  the  instrument  to  do  with 
stones  ? 

Perhaps  the  word  was  never  quite  correctly  formed,  but 
Digges's  idea  is  probably  indicated  by  his  spelling, — at  any  rate 
not  more  absurdly  than  the  previous  derivations  would  appear. 
It  looks  as  if  his  intention  had  been  to  combine  the  Greek 


NOTES    ON    MINE-SURVEYING   INSTRUMENTS.  267 


words  6£a,  or  dea-o^ai,  viewing  or  observing,  drjlos,  clear,  or 
to  make  clear,  and  ?TOC,  the  rim  of  a  round  body  ;  meaning  :  a 
distinctly  marked  rim  (or  disk)  for  viewing,  or  for  observation. 
If  so,  the  second  vowel  should  strictly  have  been  a  ;  but  even  the 
Greeks  in  like  cases  seem  to  have  slipped  into  o,  especially  in 
later  times  ;  for  example,  Theogenes  for  Theagenes,  and  several 
compounds  of  <rxtd,  as  in  the  English  sciomachy  and  sciomancy. 
But  possibly  the  first  syllable  is  from  6tto,  to  run  or  revolve  ;  so 
as  to  mean  a  revolving,  clear-making  rim  or  disk.  In  use, 
however,  the  theodelitus  was  mainly  stationary,  while  the  alidade 
moved  round.  It  may  be  objected  that  by  the  ordinary  later 
methods  of  transliterating,  the  last  vowel  should  be  y  instead  of 
u  (theodelitys)  ;  but  until  nearly  or  quite  Cicero's  time  u  would 
have  been  the  letter  to  use,  as  in  cubus,  cube.  It  is  said,  too, 
that  the  learned  Gladstone,  of  our  days,  so  transliterated  with 
u.  It  is  nothing  violent,  then,  to  suppose  that  Digges  did  like- 
wise ;  especially,  seeing  that  he  clung  so  closely  to  the  Greek 
form  as  to  give  Stratioticos,  instead  of  Stratioticus,  for  the  title  of 
one  of  his  books. 

Y.  TRANSIT. 

First  Surveying  Transit.  —  The  first  American  transit  for  sur- 
veying was,  according  to  Mr.  Scott,*  introduced  by  Wm.  J. 
Young  in  1831,  following,  however,  probably  after  "  Ramsden 
(1803),  who  introduced  the  transit  principle  in  small  English 
theodolites  at  that  time."  Also  on  page  697  Mr.  Scott  men- 
tions "  the  transit-principle  of  Ramsden  in  1803."  It  must, 
then,  have  been  of  the  "  sic  transit  gloria  mundi  "  type  ;  for 
Ramsden  died  Nov.  5,  1800.  Mr.  Scott  refers  to  no  authority; 
and  was  he  not  perhaps  thinking  of  the  portable  transit  indi- 
cated by  Mr.  Hoskold,  Fig.  80,  f  as  probably  the  one  used  in 
the  surveys  of  the  Box  Tunnel,  as  mentioned  by  Bourns  ?  Fig. 
80  is  copied  from  Simms's  figure  of  an  instrument  made  by 
Troughton  ;  and  is  clearly  not  properly  a  surveying  instrument 
at  all,  but  merely  a  portable  astronomical  instrument,  used  in 
this  case  extraordinarily  for  a  single  sight  or  two  in  a  tunnel 
survey.  It  seems  clear,  indeed,  that  the  transit  surveying-in- 
strument was  first  invented  and  used  in  America. 

But  who  was   really  the  American  inventor  of  the  transit  ? 

*  Page  25.  f  Page  111. 


268 


NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 


Mr.  Scott  gives  no  authority  for  his  statement  that  it  was  Young 
in  1831.  Others  before  Mr.  Scott  have  made  the  same  state- 
ment, and  much  color  has  been  given  it  by  Mr.  Young's  justly 
high  reputation  as  an  instrument  maker ;  but  did  Mr.  Young 

FIG.  155. 


Draper's  Early  Transit. 

himself  ever  lay  claim  to  the  invention  ?     There  appears  to  be 
no  evidence  whatever  that  he  did  so. 

Fig.  155  shows  a  transit  by  Edmund  Draper,  apparently  of 
earlier  date  than  1831,  and  supposed  by  its  owner,  Mr.  S.  Gr. 


NOTES    ON    MINE-SURVEYING   INSTRUMENTS.  269 

Frey,  of  Watsontown,  Pa.,  to  date  from  1821.  But,  as  Draper 
died  Dec.  24,  1882,  "  in  the  77th  year  of  his  age,"  according  to 
the  advertisement  of  his  death  in  the  usually  very  accurate 
Philadelphia  Public  Ledger,  he  would  have  been  only  in  his  16th 
year  in  1821,  and  could  hardly  have  invented  and  constructed 
a  transit  at  that  early  age.  Mr.  Frey  took  the  instrument 
to  Mr.  Draper  in  1874,  for  repairs ;  and  says  that  Mr.  Draper, 
then  an  old  man,  after  carefully  looking  it  over,  said :  "  Yes,  I 
made  that  transit  many  years  ago.  It  was  among  the  firSt  I 
put  out  when  I  commenced  business,  and  it  works  as  nicely 
now  as  it  did  when  first  made.  But  I  cannot  remember  to 
whom  it  was  sold,  as  I  have  not  my  old  record  at  hand."  It 
has  latterly  been  announced  that  Draper  begun  business  in 
1815,  but  at  that  time  he  must  have  been  no  more  than  in  his 
tenth  year,  and  could  have  held  only  a  very  subordinate  position 
in  any  business.  Mr.  Frey  has  had  the  transit  ever  since  1863, 
and  the  next  preceding  owner  told  him  that  he  had  had  it  since 
1834.  According  to  tradition,  it  was  made  by  Draper  in  1821, 
presumably  to  be  used  in  surveying  the  Pennsylvania  State 
canals  and  the  Reading  Railroad. 

At  all  events,  the  instrument  itself  bears  strong  evidence  of 
age,  and  has  a  decidedly  more  antique  appearance  than 
Young's ;  yet  Draper  was  certainly  never  behind  the  times,  and 
even  in  this  early  piece  of  work  shows  his  superiority  in  the  ele- 
gance of  the  proportions  of  the  vees  and  other  parts.  One  of  the 
details,  however,  that  give  the  more  antique  look  is  the  greater 
height  of  the  transit-plates  above  the  tripod ;  for  in  the  lapse  of 
years,  they  have  been  gradually  lowered  towards  the  tripod,  to 
secure  more  satisfactory  steadiness.  The  telescope  of  the 
Draper  transit  is  an  erecting  one  of  very  weak  power,  com- 
pared with  the  inverting  telescope  of  the  Young  transit,  which 
appears,  in  fact,  to  belong  to  a  much  more  advanced  stage  of 
optical  development.  Both  instruments  have  the  old  arrange- 
ments for  adjusting  the  telescope  by  shifting  one  end  of  the 
axle  so  as  to  make  the  cross- wires  cut  the  same  object  that  the 
sights  of  a  compass  cut  when  reading  the  same  magnetic  bear- 
ing from  the  same  point.  It  was  the  early  method  for  survey- 
ing transits,  but  was  soon  abandoned  for  the  present  much 
more  accurate  one  of  reversals,  for  adjusting  the  vertical  cross- 
hair, or  line  of  collimation — the  method  which  had  already 


270  NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 

been  used  with  the  astronomical  transit-telescope  (though,  in 
that  case,  with  reversal  of  the  telescope-axle  in  its  wyes,  end 
for  end).  On  looking  closely  at  the  Draper  instrument,  small 
indentations  may  be  seen  in  the  lower  parallel  leveling-plate, 
which  have  been  made  by  the  leveling-screws ;  showing  that 
the  important  device  of  placing  a  ring  or  disk  of  sole-leather  be- 
neath the  screws,  as  a  washer,  upon  the  plate  had  not  yet  been 
adopted,  as  it  may  be  perceived  to  have  been  in  the  Young 
transit.  For  the  same  purpose,  flat-bottomed  metal  cups  below 
the  screws  have  been  used,  but  are  apt  to  get  lost ;  and,  as  the 
bottom  of  the  screws  is  not  spherical,  they  are  liable  to  bind  at 
times.  Heller  &  Brightly,  in  1871,  very  satisfactorily  gained  the 
desired  end  by  introducing  a  truly  spherical  cup  and  ball  insep- 
arably attached  at  the  bottom  of  the  screws.  Draper's  transit  has 
straight  spirit-levels,  instead  of  the  round  one  seen  in  Young's ; 
for  Draper  never  would  use  the  round  level,  because  it  is  some- 
times impossible  to  seal  it  perfectly  and  permanently,  and  the 
difficulty  of  giving  its  interior  a  perfect  curvature  is  greater. 

Edmund  Draper. — Draper,  although  he  made  no  bluster  and 
noise  about  his  accomplishments,  took  great  pride  in  his  excel- 
lent skill  and  knowledge  of  his  art,  and  is  said  to  have  earn- 
estly declared  that  he  would  never  have  any  "  successor  "  in 
his  business  to  diminish  even  indirectly  his  fair  professional 
fame.  Accordingly,  after  his  death,  in  1882,  the  business 
carried  on  from  1883  to  1892  with  some  of  his  old  tools,  but 
not  even  at  the  old  stand,  by  Mr.  Robert  Wareham,  who  had 
been  one  of  his  workmen,  was  never  made  an  excuse  for  assum- 
ing the  title  of  Draper's  successor.  Later,  after  Mr.  Ware- 
ham's  death,  a  young  man  who  had  never  worked  with  either 
Draper  or  Wareham,  continued  business  at  Wareham's  place, 
with  possibly  some  of  Draper's  apparatus ;  and  now  advertises 
himself  as  "Draper's  successor."  It  must  be  done  on  the 
ground  merely  of  being  subsequent  to  him,  without  any  idea 
that  Draper  or  others  would  consider  it  an  impropriety  so  to 
use  his  name,  as  an  indication  presumably  of  an  authorized 
continuance  of  his  skill  and  reputation. 

VI.  INSTRUMENT-PARTS. 

Ramsden's  Dividing-Engine. — Mr.  Scott  says*  "  Jesse  Rams- 
den  had  already  (1760)  constructed  a  circular  dividing-en- 

*  Page  16. 


NOTES    ON    MINE-SURVEYING   INSTRUMENTS.  271 

gine,"  and  is  apparently  corroborated  by  Mr.  Hoskold.*  In 
1760  Ramsden  was  in  the  midst  of  the  fourf  years'  apprentice- 
ship which  he  had  begun  in  1758,J  after  coming,  at  the  age  of 
twenty,  to  London  in  1755.  It  was  only  in  1777  that  he  pub- 
lished a  description  of  his  celebrated  dividing-engine,  presum- 
ably just  completed;  and  he  was  thereupon  rewarded  by  the 
Board  of  Longitude. 

Fineness  of  Graduation. — Mr.  Hoskold  is  quite  right  in  his 
conclusion  §  that,  as  regards  precision  of  the  graduation,  "  there 
is  a  medium  course,"  and  that  "  it  is  necessary  to  determine 
the  fineness  of  the  divisions  .  .  .  according  to  the  nature  of  the 
work  and  the  degree  of  accuracy  sought  to  be  attained."  But 
his  illustration  of  the  inaccuracy  of  coarser  divisions  is  not 
very  convincing.  He  arbitrarily  supposes  certain  observed  an- 
gles with  a  graduation  to  minutes,  and  shows  the  result  of  a 
whole  minute  of  error  in  the  sum  of  an  angle  and  its  supple- 
mentary angle.  But  a  reading  to  the  nearest  minute  (which  is 
probable)  and  consistently  with  the  two  other  suppositions 
would  have  shown  no  such  error,  and  according  to  his  reason- 
ing would  have  proved  complete  accuracy ;  although  the  true 
angle  might  have  differed  by  twenty  seconds  from  the  observa- 
tion. Indeed,  if  his  three  supposed  cases,  with  graduations  to 
one  minute,  twenty  seconds  and  fifteen  seconds,  were  made 
consistent  with  each  other  and  with  the  graduations,  and  the 
readings  made  to  the  nearest  graduation,  the  result  in  each 
case  would  show  complete  accuracy  in  the  sum  of  the  angles, 
and  consequently,  according  to  him,  complete  accuracy  in  the 
observations,  as  follows : 

Angle,    ....     164°  32'  0"        164°  31'  40"        164°  31'  45" 
Supplementary  angle,     .     195°  28'  0"         195°  28'  20"         195°  28'  15" 

360°     0'  0"         360°     0'     0"         360°     0'     0" 

The  true  angles  may  be  near  either  of  the  pairs  observed 
with  the  two  more  precise  graduations,  or  may  be  between 
them.  Clearly,  the  angle  and  its  supplementary  angle,  if  both 
were  read  correctly  to  the  nearest  graduation,  will  always  sum 
up  360°;  except  that  an  error  might  occur  when  the  truth  is 

*  Page  96.  f  Grant,  p.  490. 

J  Diet.  Nat.  Biog.  §  Page  114. 


272  NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 

exactly  half-way  between  two  graduations,  so  that  a  reading 
might  be  made  in  one  case  or  the  other  that  would  cause  an 
error  to  the  extent  of  one  graduation  in  the  sum. 

Conical  Graduation. — Mr.  Hoskold  says*  that  graduations 
upon  a  conical  or  bevel-edge  form  are  more  easily  read  than 
those  upon  a  flat  surface.  They  are,  indeed,  slightly  easier  to 
read;  because  the  eye  is  placed  a  little  more  conveniently  in  a 
line  at  right  angles  with  the  slope  of  the  bevel-edge,  instead  of 
vertically  over  a  horizontal  plate.  But  the  sloping  graduations 
are  disliked  by  instrument-makers,  because  more  troublesome 
from  the  increased  difficulty  of  correcting  the  centering  and  of 
getting  the  vernier  precise;  and  therefore  repairs  are  much 
more  expensive. 

Full  Vertical  Circle. — Mr,  Hoskold  says,f  against  Mr.  Stan- 
ley's using  a  full  vertical  circle  with  only  one  vernier,  that  the 
only  advantage  of  the  full  circle  is  thereby  lost.  But  the  full 
circle  has  the  very  important  additional  advantage  that  it  ena- 
bles the  constructor  to  test  the  placing  of  the  vernier  so  thor- 
oughly as  to  make  it  trustworthy.  A  second  vernier  would 
give  the  same  reading  as  the  first,  and  would  therefore  be 
rarely  used,  if  at  all. 

Leveling-Screws. — Mr.  Hoskold  saysj  that,  "  by  preference,  a 
triangular  leveling  and  centering  frame  of  light  weight,  with 
three  leveling-screws,  is  attached  to  the  theodolite;"  and  Mr. 
W.  F.  Stanley  says§  that  "the  growing  sentiment  in  Eng- 
land is  greatly  in  favor  of  three  leveling-screws."  In  America, 
four  leveling-screws  are  constantly  preferred  to  three,  and  ap- 
parently with  good  reason.  Not  only  is  the  leveling  effected 
more  conveniently  and  speedily  with  four  screws  than  with 
three,  because  both  hands  work  at  the  same  time,  and  conse- 
quently only  one-half  the  time  that  one  screw  would  require  in 
bringing  each  level-bubble  to  its  •  proper  place ;  but  also  the 
construction  of  the  tripod-head  necessitated  by  the  three  screws 
is  decidedly  less  satisfactory  than  when  there  are  four.  With 
four  screws,  the  transit  simply  moves  about  a  ball-and-socket 
joint  in  the  tripod-head;  but,  with  three  screws,  that  arrange- 
ment is  impossible,  and  the  transit  either  rests  by  its  own 

*  Page  113.  f  Page  210. 

1  Page  103.  I  Page  76. 


NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 


273 


weight,  without  any  binding  attachment,  upon  a  roughly  hori- 
zontal plate  at  the  top  of  the  tripod,  or,  more  usually  and  more 
securely,  is  united  to  the  tripod  by  a  central  vertical  shaft  that 
is  surrounded  by  a  very  strong  spiral  spring  some  five  inches 
long,  against  which  the  leveling-screws  pull.  (See  Figs.  156 
and  157,  copied  from  Bauernfeind,  pp.  188  and  340.)  The 
spring,  after  being  in  one  position  for  some  time,  "  takes  a  set," 
or  relaxes  slightly,  and  the  transit  ceases  to  be  in  perfect  level, 


FIG.  156. 


Three  Leveling-Screw  Method. 

and  needs  to  be  leveled  up  anew.  At  each  removal  of  the  in- 
strument from  the  tripod,  the  shaft  must  be  unscrewed  by  a 
milled-head  at  its  lower  end  from  the  socket  of  the  instrument 
center  above ;  and  on  replacing  the  instrument,  must  be  screwed 
on  again,  and  another  milled-head  nut  must  be  turned  to  adjust 
the  spring.  For  packing  the  instrument  a  specially  arranged 
box  is  necessary  that  is  less  convenient  than  the  arrangement 
that  is  possible  with  four  leveling-screws,  and  cannot  be  made 


274  NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 

safely  to  protect  the  instrument  from  injury,  as  it  can  with  the 
four  screws.  Four  leveling-screws,  then,  are  decidedly  prefer- 
able to  three  on  the  ground  both  of  greater  ease  in  operation, 
and  of  the  still  more  important  exigencies  of  accuracy  in  use 
and  of  safety  and  convenience  in  carrying. 

In  general  the  English  tripod-heads  with  four  leveling- 
screws  give  a  very  narrow  base  for  the  leveling-screws  and  for 
the  top  of  the  tripod  legs,  and  are  consequently  unsteady  com- 
pared with  the  American  form.  But  the  three  leveling-screws 
requiring  a  wider  base  are  more  steady  than  the  English  four- 

FIG.  157. 


Three  Leveling-Screw  Method. 

screw  form,  though  too  cumbersome  to  suit  American  engineers. 
That  advantage  of  the  three  leveling-screws  may  explain  the 
preference  for  them  that  Mr.  Hoskold  and  Mr.  Stanley  say  now 
exists  in  England. 

Shifting  Tripod-Heads. — Mr.  Hoskold  describes  and  illustrates* 
Troughton  &  Simms's  shifting  tripod-head,  and  says  it  is  their 
invention.  It  is,  however,  essentially  Edmund  Draper's  shift- 
ing tripod-head,  with  the  addition  of  a  clamping-plate  to  adapt 
it  to  use  with  three  leveling-screws.  Within  a  year  after  Young 
in  1858  patented  the  shifting  tripod-head  now  claimed  by  Hul- 
bert  as  his  own  suggestion  to  Young,  Draper,  to  attain  the 

*  Page  212. 


NOTES    ON    MINE-SURVEYING    INSTRUMENTS. 


275 


highly  important  object  of  the  device  and  yet  to  avoid  infring- 
ing upon  Young's  patent,  very  ingeniously  contrived  his  own 
method,  but  did  not  have  it  patented.  It  is  shown  in  Fig.  158.* 
There  are  two  horizontal  brass  plates,  about  4  in.  by  8  in., 
large  enough  to  give  great  stability,  the  lower  plate  fixed  upon 
the  top  of  the  tripod,  and  the  upper  or  shifting-plate  capable 
of  moving  in  any  direction  upon  the  lower  one,  within  a  radius 
of  about  an  inch,  but  restrained  from  wider  movement  by  a 
small  pin  in  a  narrow  slot  near  each  end  of  each  plate,  the 
slots  of  one  plate  at  right  angles  to  those  of  the  other.  The 

FIG.  158. 


Draper's  Shifting  Tripod-Head,  with  One  Nut  Removed. 

pins  have  a  shoulder  at  the  bottom  and  a  screw-thread  on  their 
upper  part,  and  the  plates  may  be  clamped  together  by  a  milled- 
head  nut  on  each  pin.  The  ball-socket  is  a  part  of  the  upper 
plate  at  its  center.  Upon  the  upper  or  shifting-plate  rest  the 
four  leveling-screws.  Draper's  tripod-head  has  a  larger  move- 
ment than  Young's,  and  in  spite  of  its  bulkier  form  is  still  pre- 
ferred by  some  engineers,  and  is  still  manufactured.  Its  main 
objections  are  that  the  clamping-screws  are  liable  to  get  lost  in 
the  field,  and  the  large  plates  to  get  slightly  bent  and  conse- 
quently useless. 

*  See  also  Fig.  35,  p.  39,  with  a  brief  reference  to  the  device. 

19 


276  NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 

About  1864,  Mr.  Chas.  S.  Heller  (now  of  Heller  &  Brightly) 
contrived  a  shifting  tripod-head,  still  in  use,  that  is  readily  ap- 
plicable to  any  old  instrument,  and  precisely  similar  in  princi- 
ple to  Mr.  Hoskold's  tripod-head  of  1866.*  A  4  in.-broad 
annular  plate,  or  flat  ring,  of  brass,  with  a  wide  hole  in  the 
middle  for  the  shank  of  the  instrument,  and  for  the  four  level- 
ing-screws,  and  with  a  screw-thread  cut  inside  of  a  down-hang- 
ing flange  at  the  rim,  screws  down  upon  the  tripod-top,  clamp- 
ing the  shifting-plate  between  it  and  the  tripod-top.  The  four 
leveling-screws  rest  upon  the  shifting-plate.  When  the  transit 
with  the  leveling-head  is  carried  from  one  station  to  another, 
the  clamping-plate  hangs  loose,  making  a  little  racket;  and 
that  small  objection  is  the  principal  one  against  the  arrange- 
ment. 

Hoffman-Harden  Tripod-Head. — Notwithstanding  the  ingenu- 
ity and  the  theoretically  probable  effectiveness  of  the  Hoffman 
tripod-head,  with  or  without  the  Harden  improvement,  appar- 
ently certain  difficulties  in  practical  use  have  caused  dissatis- 
faction. The  least  dust  upon  the  upper  half-ball  prevents 
smooth  working ;  and  a  somewhat  larger  grain  of  grit  there 
plows  into  the  metal,  and  completely  destroys  the  efficiency  of 
the  appliance.  The  upper  half-ball  unduly  increases  the  height 
of  the  instrument.  The  number  of  joints  between  the  tripod 
and  the  telescope  makes  the  instrument  comparatively  un- 
steady. The  approximate  parallelism  of  the  parallel  plates  of 
the  tripod  may  be  maintained  without  the  device  by  merely 
careful  setting  of  the  tripod-legs,  without  or  with  extensible 
legs  ;  as  intimated  by  Mr.  Hoskold.f 

Heller  £  Brightly' s  Improvements. — In  1871,  Messrs.  Heller  & 
Brightly  introduced  several  important  improvements  in  the  con- 
struction of  the  transit.  See  the  report  on  them  by  the  remark- 
ably able  committee  of  the  Franklin  Institute.  The  weight  of 
the  transit  was  diminished  about  one-half  by  using  cast  bronze, 
cast  under  great  hydrostatic  pressure — with  a  "  high  gate  " — 
instead  of  hammered  sheet  brass,  and  by  ribbing  and  bracing 
the  plates,  with  the  removal  of  superfluous  metal.  An  experi- 
ence of  almost  thirty  years  has  now  amply  proved  the  wisdom 
of  the  change  of  metal,  though  the  excessively  conservative 

*  Page  214.  t  Page  211. 


NOTES    ON    MINE-SURVEYING    INSTRUMENTS.  277 

long  maintained  their  doubts  about  so  radical  a  departure  from 
old  practice.  The  method  of  attaching  and  detaching  the  in- 
strument on  the  tripod  was  also  improved  by  means  of  three 
lugs  on  the  upper  parallel  plate  of  the  tripod-head,  all  corres- 
ponding to  recesses  in  a  flange  around  the  exterior  of  the 
socket  enclosing  the  compound  center,  and  one  of  the  lugs  be- 
ing movable,  so  as  to  clamp  the  socket  after  turning  the  in- 
strument until  the  lugs  are  away  from  the  recesses  in  the 
flange.  The  tripod  leveling-head  was  separately  detached  from 
the  tripod.  So  detaching  the  transit  proper,  or  level,  with  its 
long  center  from  the  tripod  leveling-head,  and  this  head  sepa- 
rately from  the  tripod,  enables  the  instrument  to  rest  securely 
in  its  packing-box  in  precisely  the  same  way  as  it  does  upon  the 
tripod-head.  Though  more  difficult,  it  is  a  securer  plan  than 
the  ordinary  one,  and  makes  it  possible  to  carry  the  instrument 
safely  to  distant  countries.  Owing  to  the  great  reduction  in 
the  weight  and  to  the  readier  method  of  attaching  and  detach- 
ing the  transit  from  the  tripod-head,  the  compound  center  be- 
came feasible  for  ordinary  use,  instead  of  being  virtually  con- 
fined to  the  most  accurate  city-  and  tunnel-surveying.  By 
degrees  other  makers  have  now  adopted  the  same  methods,  so 
that  the  compound  center  has  at  length  become  common  every- 
where ;  and  the  "  flat  center "  comparatively  rare,  with  its 
friction  between  the  plates,  the  quick  wearing  of  the  graduated 
plate  around  the  shallow  center,  and  the  consequent  inaccuracy 
of  work,  and  with  the  exposure  of  the  spindle,  or  turning-cen- 
ter of  the  entire  instrument,  whenever  the  transit  is  detached 
from  the  tripod-head. 

Heller  &  Brightly  also  used  a  tangent-screw  that  overcame  all 
lost  motion,  by  means  of  a  spiral  spring  that  constantly  presses 
the  screw  away  from  its  supporting  nut,  not  with  the  spring 
opening  and  closing  to  the  extent  of  the  whole  motion  of  the 
screw,  but  merely  to  the  extent  of  the  backlash,  by  pressing 
against  a  detached  follower  within  the  nut.  They  extended  the 
slits  in  the  clamps  on  the  axis  of  the  telescope  downwards 
almost  to  the  bottom  of  the  clamps,  and  made  sighting-holes  in 
the  slits ;  so  that  an  accurate  sight  at  right  angles  to  the  tele- 
scope can  be  made.  They  made  the  tripod  legs  of  semicircular 
cylinders  sliding  on  one  another's  plane  surface  and  clamping 
in  any  position ;  so  as  to  give  a  play  of  from  three  to  five  feet 


278 


NOTES    ON    MINE-SURVEYING    INSTRUMENTS. 


in  length  of  legs.  The  tripod-head  and  the  cheeks  for  the  legs 
were  made  of  one  piece ;  so  as  to  prevent  the  possibility  of  un- 
steadiness there;  and  the  top  of  each  leg  enclosed  a  single 
cheek,  instead  of  being  enclosed  by  two  cheeks.  Pure  plum- 
bago was  used  as  a  lubricant  for  all  the  screws,  preventing  hard 

work  in  cold  weather. 

FIG.  159. 


flF 


Heller  &  Brightly' s  Mining- Transit. 

One  small  device  of  theirs  is  a  great  convenience  in  setting 
the  transit  precisely  under  a  plumb-bob  hanging  from  the  top 
of  a  mine  gangway.  For  that  purpose,  a  small  screw  in  the 
center  of  the  top  of  the  axle,  or  the  binding-screw  there  that 
fixes  the  telescope  in  its  axle,  has  a  minute  hole,  say  -^  in.,  or 
less,  in  diameter,  by  a  special  apparatus  drilled  in  the  top  ex- 
actly in  the  center  of  the  axis  of  rotation  of  the  transit.  This 
form  of  the  device  dates  back  to  about  1884;  but  from  1874, 


NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 


279 


the  same  object  was  effected  by  a  small  brass  plate  with  adjust- 
ing-screws, and  with  the  center  marked  by  two  lines  crossing 
at  right  angles. 

Heller  &  Brightly  also  constructed  a  mining-transit  (Figs. 
159  and  160),  described  by  Dr.  Raymond  at  our  meeting  of 
February,  1873  (Trans.,  Vol.  L,  p.  375).  It  was  a  close  copy 

FIG.  160. 


Heller  &  Brightly 's  Mining-Transit. 

ot  their  complete  engineer's  transit,  but  of  reduced  dimensions, 
making  it  the  lightest  American  transit  that  had  then  been 
made.  It  had  an  erecting  telescope  7  J  inches  long ;  extreme 
diameter  of  plates,  5  inches ;  plate-graduation  circle,  4J  inches 
in  diameter ;  a  three-inch  compass-needle ;  long  compound  cen- 
ters ;  height  of  the  instrument  from  the  tripod  legs,  7  inches ; 
weight  in  all,  about  5|  pounds ;  besides  a  tripod  of  3  J  pounds. 


280  NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 

At  that  time,  a  prism  and  tube  were  provided  to  attach  to  the 
eye-piece  of  the  telescope,  for  sighting  vertically  upward  in 
shafts ;  but  (as,  notwithstanding  Mr.  Hoskold's  argument*  that 
sighting  a  telescope  up  a  shaft  gives  the  same  angular  result  as 
sighting  down  it,  the  sight  cannot  be  equally  satisfactory  if 
water  be  dripping  abundantly  upon  the  upturned  object-glass) 
by  1876  a  side-telescope  was  adjusted  so  as  to  be  parallel  to  the 
central  one,  and  was  placed  removably  at  the  end  of  the  main 
telescope  axle  opposite  to  the  vertical  arc.  The  effect  of  the 
eccentricity  of  the  telescope  can  be  corrected  either  by  com- 
putation, or,  more  conveniently,  by  using  a  lop-sided  or  a  double 
target.  Mr.  Hoskbldf  speaks  of  Combes  and  "  the  use  of  his 
double  target."  But  it  does  not  appear  that  Combes  ever  used  a 
double  target,  or  even  a  lop-sided  single  one.  The  double  target 
given  by  Scott  in  Fig.  23^J  appears  to  be  of  decidedly  later 
date.  Heller  &  Brightly  later  replaced  the  side  telescope  by  an 
auxiliary  top  telescope,  supported  by  two  pillars,  fore  and  aft, 
upon  the  main  telescope ;  for  the  testing  of  the  adjustment  is 
far  more  convenient  than  with  a  side  telescope,  and  a  counter- 
poise, though  quite  feasible,  yet  so  liable  to  be  lost  by  a  fallible 
mortal  of  a  surveyor,  is  less  necessary  on  account  of  the  less 
serious  effect  of  the  weight  of  a  top  telescope,  from  its  not 
tending  to  pull  itself  and  the  main  telescope  away  from  the 
correct  vertical  plane.  The  sights  taken  with  the  auxiliary  tel- 
escope are,  of  course,  comparatively  very  few,  and  at  other 
times  it  is  packed  away  with  its  pillars  in  the  transit  box,  or  in 
the  surveyor's  satchel,  leaving  the  instrument  wholly  unincum- 
bered  and  free  from  uneven  wear  of  the  center,  even  if  there 
be  no  counterpoise.  In  using  a  top  telescope,  the  correction  of 
the  observed  angle  for  eccentricity  from  the  center  of  revolution 
should  not  be  neglected,  especially  in  short  sights ;  most  conve- 
niently by  computation  or  by  a  small  table.  A  small  remova- 
ble metallic  reflector  in  the  shape  of  a  quadrant  of  a  cylinder, 
to  facilitate  the  reading  of  angles,  was  in  1873  applied  just 
behind  the  vernier  opening;  also  there  was  a  small  adjustable 
lamp-stand  easily  fastened  upon  one  leg  of  the  tripod,  and 
quickly  set  so  as  to  illuminate  the  cross-wires  of  the  verniers. 
These  last  attachments  are  likewise  useful  in  astronomical  ob- 

*  Page  231.  t  Page  108.  J  Page  28. 


NOTES    ON    MINE-SURVEYING   INSTRUMENTS.  281 

servations  with  the  larger  transit,  in  determining  the  true  me- 
ridian. 

Such,  at  that  time,  revolutionary  improvements  in  transits 
well  deserved  the  generous  encomiums  of  Prof.  J.  B.  Davis,  of 
the  University  of  Michigan,  in  describing  Heller  &  Brightly's 
exhibits  at  the  Centennial  World's  Fair.  He  says : 

"  I  think  their  most  valuable  contribution  to  the  advancement  of  their  busi- 
ness is  the  spirit  of  invention  and  adaptation  which  they  have  awakened  amongst 
their  competitors.  .  .  .  One  is  surprised  at  every  point,  in  examining  the  work  of 
this  Philadelphia  firm,  to  see  the  extreme  care  and  judgment  with  which  every 
detail  is  worked  out.  One  cannot  well  help  referring  the  work  of  other  makers 
to  theirs  as  a  kind  of  standard  with  which  to  compare  it." 

Indeed,  it  is  quite  incomprehensible  how  anybody  in  under- 
taking to  write  up  "  The  Evolution  of  Mine-Surveying  Instru- 
ments," with  special  allusions,  moreover,  to  nearly  every  other 
surveying  instrument  directly  or  indirectly,  even  very  remotely, 
connected  with  them,  could  have  wholly  failed  to  discover  and 
mention  an  American  establishment  so  prolific  in  important  im- 
provements in  that  line  and  so  eminent  in  every  branch  of  their 
business.  The  firm  was  established  after  the  death  of  Wm.  J. 
Young  in  July,  1870.  The  head  and  soul  of  the  firm,  Mr. 
Charles  S.  Heller,  had  been  fifteen  years  with  Mr.  Young,  the 
last  five  years  of  Mr.  Young's  life  as  his  only  partner.  Mr. 
Brightly  was  one  of  their  most  skilful  workmen.  Mr.  Brightly 
retired  from  the  firm  in  1889,  and  died  in  1893. 

VII.  OTHER  INSTRUMENTS  AND  APPLIANCES. 

In  a  general  account  of  "  the  evolution  of  mine-surveying 
instruments  "  several  important  improvements  should  not  have 
been  omitted  that  Mr.  Scott  seems  to  have  overlooked. 

Sunflower. — An  instrument  that  has  been  found  very  conve- 
nient for  measuring  the  cross-section  of  tunnels  is  called  the 
Sunflower  (Fig.  161).  It  was  first  made  by  Heller  &  Brightly 
from  the  design  of  Alfred  Craven,  a  division  engineer  on  the 
Croton  Aqueduct,  and  was  published  in  1887.*  It  is  a  wooden 
disk  about  15  inches  in  diameter,  graduated  to  degrees,  sup- 
ported vertically  by  a  tubular  rod  upon  a  tripod  with  extension- 
legs,  and  having  across  the  center  of  the  disk  a  wooden  arm, 

*  The  Sanitary  Engineer  and  Construction  Record,  New  York,  June  11,  1887. 
See  also  Trans.  Am.  Soc.  C.  E.,  xxiii.,  July,  1890,  pp.  17-38. 


282 


NOTES    ON    MINE-SURVEYING    INSTRUMENTS. 


metal-shod  at  the  ends,  that  revolves  on  the  plane  of  the  disk, 
and  bears  a  long  graduated  wooden  rod  sliding  on  the  upper 
surface  of  the  arm.  There  are  two  small  levels  for  exactly  plumb- 
ing the  rod  that  supports  the  disk ;  and  there  is  a  sighting  tube 
with  cross-wires  for  testing  the  precise  adjustment  of  the  cen- 
ter of  the  disk  to  the  center  of  the  tunnel.  One  end  of  the 

FIG.  161. 


Heller  &  Brightly 's  Sunflower,  Front  View,  with  an  Extension-Tripod. 

wooden  rod  touches  the  perimeter  of  the  tunnel,  while  the  dis- 
tance is  read  with  a  vernier  at  the  center  of  the  disk.  The 
distances  are  taken  at  any  desired  number  of  angles  around  the 
whole  disk,  and  are  plotted  conveniently  with  a  protractor. 
(See  Fig.  163.)  The  time  required  to  measure  a  section  of  the 
tunnel  is  from  six  to  ten  minutes.  The  weight  of  the  disk  in- 
cluding all  attachments  is  10  pounds,  and  the  tripod-head  with 


NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 


283 


an  extension-leg  tripod  weighs  10  J  pounds,  making  a  total 
weight  of  20J  pounds.  There  are  two  measuring-rods,  8  and 
14  feet  long.  The  instrument  is  also  useful  for  testing  masonry 
work  after  the  centers  are  struck. 

Plummet-Lamp. — Eckley  B.   Coxe's  plummet-lamp   was  de- 
scribed by  Dr.  Kaymond,  then  President  of  our  Institute,  and 

FIG.  162. 


Heller  &  Brightly' s  Sunflower,  Side  View. 

its  use  explained  by  Mr.  Coxe  himself  in  papers  read  before  the 
meeting  of  February,  1873,*  and  was  soon  published  in  sev- 
eral journals.  The  lamp  was  made  by  Heller  &  Brightly,  and 
was  contrived  for  use  in  accurate  mine-surveying  to  take  the 
place  of  the  open  mine-lamp  set  (if  not,  as  too  often  happened, 
overset)  on  the  ground,  or  of  the  mere  string  of  a  plumb-bob 

*  Trans.,  i.,  378. 


284 


NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 


with  or  without  a  light  or  a  white  surface  behind  it.  The  plum- 
met-lamp, as  eventually  made,  rests  by  trunnions  on  a  horizontal 
"  compensating  "  ring,  which  at  points  90°  from  the  trunnions  is 
hung  by  two  light  short  chains  from  a  cord  that  depends  from 
a  spud  (a  nail  with  a  hole  in  the  head)  driven  into  the  mine 
timber  over  a  station,  or  into  a  wooden  plug  inserted  in  a  hole 
drilled  in  the  coal  or  rock  roof.  Mr.  Coxe  found  that  with  the 
plummet-lamp  "  two  persons  can  make  a  very  accurate  survey 
as  quickly  as  three  can  by  the  old  method." 

Chains  and  Tapes. — Mr.   Scott*  says  "  the   chain  of  Ritten- 

FIQ.  163. 


Tunnel  Section-Measuring  with  the  Sunflower. 

house,  which  comprised  80  links  or  66  feet,  was  quite  gen- 
erally used  in  American  mines."  Gunter's  chain  of  66  feet 
with  100  links  is  about  150  years  older  than  Rittenhouse,  and 
it  would  be  interesting  to  know  why  80  links  should  be  used 
instead  of  100.  I  have  not  discovered  any  reference  to  so  sin- 
gular an  arrangement  in  any  of  the  numerous  works  on  Kitten- 
house  or  by  him. 

Eckley  B.  Coxe  was  also  the  first  to  introduce,  with  Heller  & 
Brightly's  aid,  the  use  of  the  long  steel  tape,  or  "  chain-tape," 
at  first  500  feet  long,  afterwards  up  to  1000  feet,  instead  of 
chaining.  Formerly  the  graduation  scratched  on  the  tape,  or 

*  Page  32. 


NOTES    ON    MINE-SURVEYING    INSTRUMENTS.  285 

marked  with  rivets,  would  often  occasion  breaking ;  or  if  etched 
on  the  tape,  or  marked  on  a  thin  layer  of  solder  or  tin,  were  not 
very  legible  or  easy  to  find,  and  were  easy  to  efface ;  the  steel 
ribbon  was  soft,  not  tempered,  and  was  consequently  liable  to 
alterations  in  length;  and  there  was  no  reel.  Heller  & 
Brightly  obviated  all  those  difficulties.  They  soldered  a 
small  piece  of  brass  wire  with  white  solder  across  a  tempered 
steel  ribbon,  with  the  solder  for  greater  conspicuousness  ex- 
tending about  an  inch  each  side  of  the  wire.  The  wire  had  a 
small  notch  at  the  exact  end  of  the  foot.  They  countersunk 
figures  in  the  solder  so  that,  no  matter  how  dirty  the  tape,  the 
figures  are  easily  read,  from  being  filled  with  dirt  when  the 
solder  is  wiped  off  with  the  finger.  The  tape  is  stronger  at 
the  graduations  than  anywhere  else.  Only  every  tenth  foot  is 
marked,  and  a  five-foot  rod  is  used  for  measuring  the  intermedi- 
ate feet.  The  tape  has  a  single  wooden  reel,  with  two  detach- 
able brass  handles  for  use  with  the  tape.  Coxe  gives  in  his 
paper  the  details  of  one  out  of  three  equally  good  surveys  with 
the  tape,  showing,  thanks  to  the  tape,  extraordinarily  accurate 
work  for  that  kind  of  mine  surveying. 

VIII.  SCOTT'S  TACHYMETER. 

In  regard  to  Mr.  Scott's  own  instrument  of  1896,  which* 
"  he  ventures  to  assert,  by  its  peculiar  yet  simple  construction, 
embraces  the  advantages  and  eliminates  the  disadvantages  of 
all  other  types,"  it  may  be  unpardonable  skepticism  to  doubt 
in  the  least  degree  its  surpassing  merits.  Yet  it  does  seem, 
after  all,  to  fall  in  some  points  a  little  short  of  absolute  perfec- 
tion. 

He  says  the  auxiliary  telescope  has  instead  of  cross-hairs  a 
single  one  that  is  vertical  when  that  telescope  is  on  top  and 
horizontal  when  at  the  side.  Apparently,  then,  no  point  of 
observation  can  be  fully  fixed,  with  both  horizontal  and  vertical 
angles,  without  taking  two  sights,  with  the  telescope  in  both 
positions, — obviously  a  serious  inconvenience.  It  does,  more- 
over, seem  to  an  obtuse  skeptic  that  it  would  be  more  practical 
to  have  the  supporting  pillar  of  the  auxiliary  joined  to  it  (in 
one  piece,  if  you  please — in  that  case,  wholly  giving  up  the 

*  Page  61. 


286  NOTES    ON    MINE-SURVEYING   INSTRUMENTS. 

unsatisfactory  side  use)  and  removable  with  the  auxiliary, 
rather  than  to  have  the  pillar  always  sticking  up  from  the  main 
telescope,  and  much  exposed  to  injury,  especially  in  a  mine. 

Furthermore,  the  lack  of  a  compass  seems  to  be  a  defect  of 
some  importance  ;  but  P.  &  R.  Wittstock's  detachable  compass* 
in  the  place  of  the  auxiliary  above  the  main  telescope,  and  in- 
capable of  use  when  the  telescope  is  at  all  inclined,  does  not 
seem  to  be  altogether  practical,  although  Mr.  Hoskoldf  has 
adopted  a  like  situation  for  the  compass,  and  distinctly  recom- 
mends that  method.  J  The  U-shaped  standards  made  possible 
by  dispensing  with  the  compass  hardly  seem  by  their  grace  or 
any  other  peculiar  merit  to  make  up  for  the  loss  of  the  com- 
pass. They  are  made  of  aluminum ;  notwithstanding  the  late 
firm  of  Buff  &  Berger,  makers  of  this  instrument,  used  to  argue 
strongly  and  with  much  reason  in  their  catalogue  against  the 
use  of  aluminum  in  surveying  instruments,  because  its  coeffi- 
cient of  expansion  for  temperature  is  so  different  from  that 
of  the  other  metals  with  which  it  must  be  replaced  at  the 
bearings  and  graduations,  that  the  working  results  become 
very  unsatisfactory  as  regards  accuracy.  But  we  are  told§ 
the  standards  "  will  doubtless  come  into  general  use,"  and, 
of  course,  the  instrument  too.  The  inventor's  charming  zeal 
cannot  but  make  us  hope  that  our  "  old-time  fancies "  and 
doubts  may  indeed  have  to  melt  away  before  such  success  in 
actual  practice,  the  true  test. 

IX.  NOMENCLATURE  AND  CLASSIFICATION. 

Names. — The  names  of  surveying-instruments  have  varied 
differently  from  the  instruments  themselves,  and  have  been 
used  so  diversely  as  to  deserve  a  little  elucidation  and  strict  defi- 
nition. In  some  cases  a  new  name  has  been  devised  without 
any  radically  important  change  in  the  instrument;  but  more 
often  the  same  name  has  been  applied  to  somewhat  radically 
different  instruments,  one  form  having  been  derived  from  an- 
other by  repeated  gradual  improvements  before  a  change  of 
name  was  considered  necessary. 
*  For  example,  the  name  astrolabe,  given,  as  appears  from 

*  Page  145.  f  Page  101. 

t  Page  220.  %  Page  64. 


NOTES    ON    MINE-SURVEYING    INSTRUMENTS.  287 

Reinhold,  in  1781,  to  a  mere  semicircle  with  two  fixed  sights 
and  a  movable  alidade  bearing  sights,  and  150  years  earlier* 
applied  to  a  copper  disk  for  astronomical  observations,  hung 
vertically,  with  such  an  alidade,  but  with  no  fixed  sights,  was 
still  used  by  Reinhold,  after  the  addition  of  various  improve- 
ments, for  an  instrument  that  is  essentially  a  theodolite,  with  a 
vertical  semicircle  below  a  telescope,  with  verniers  upon  the 
horizontal  alidade,  with  a  compass  and  with  an  auxiliary 
side-telescope,  Fig.  106.  (Page  168.)  It  seems  clear  that, 
instead  of  calling  a  theodolite  an  astrolabe,  even  though  it  be 
plainly  developed  from  the  astrolabe,  the  word  astrolabe  should 
at  the  present  day  be  used  only  for  the  simpler  forms,  the  forms 
to  which  it  belonged  before  the  invention  of  special  names  for 
the  improved  and  essentially  altered  forms. 

The  name  dial  seems  to  have  been  derived  from  the  gradua- 
tion of  a  disk  with  the  hours  of  the  day  ;  but  has  been  applied, 
particularly  in  England,  to  a  compass  used  in  mine-surveying. 

Circumferentor  is  a  name  that  belongs  strictly  to  a  compass 
that  is  graduated  continuously  up  to  360°. 

The  Msenscheibe,  or  iron-disk,  of  Germany  is  a  graduated 
brass  disk  turning  horizontally  and  vertically  in  any  plane  by 
means  of  a  ball-and-socket  joint,  and  with  twro  arms  revolving 
upon  the  disk  about  its  center,  each  hooked  at  the  end  to  re- 
ceive the  measuring  cords,  and  without  a  compass,  and  without 
either  sights  or  a  telescope. 

The  graphom&tre  of  Gensanne  (1770)  appears  from  Schmidt's 
descriptionf  to  have  been  merely  an  astrolabe  of  a  simple  form. 
But  Komarzewski's  graphometre  (1795)  was  an  Msenscheibe 
(iron-disk)  with  the  addition  of  a  vertical  arc  of  120°,  the  con- 
vexity upwards,  upon  the  horizontal  alidade. 

The  compass  has  as  its  principal  feature  the  reference  of  all 
horizontal  angles  to  the  meridian  by  means  of  a  magnetic  nee- 
dle and  a  graduated  ring;  and  may  have  either  sights  or  a 
telescope.  If  there  be  a  special  graduated  plate  for  horizontal 
angles  and  a  telescope  and  a  vertical  circle  or  arc,  the  instru- 
ment becomes  either  a  theodolite  or  a  transit,  and  the  compass 
becomes  a  subordinate  accessory.  In  the  solar  compass  the 
meridian  is  taken  from  the  position  of  the  sun. 


* 


The  Art  of  Navigation,  Martin  Cortes,  Seville,  1556.     Cited  in  Encyl  Britan., 
under  Navigation.    See  Fig.  105,  p.  167.  f  Page  85. 


288  NOTES    ON    MINE-SURVEYING    INSTRUMENTS. 

The  theodolite  is  capable  of  measuring  both  horizontal  and 
vertical  angles,  with  a  graduated  horizontal  plate  and  a  vertical 
semicircle  below  the  telescope  or  the  sight-bearing  alidade. 
The  telescope  or  sights  can  move  a  number  of  degrees  verti- 
cally, but  cannot  revolve  completely  in  the  vertical  plane.  As 
we  have  seen,  Digges's  topographical  instrument  was  essentially 
the  modern  theodolite  in  its  most  important  distinctive  princi- 
ples. His  theodelitus,  however,  was  merely  an  astrolabe  used 
for  horizontal  angles  instead  of  only  for  vertical  ones. 

The  transit  likewise  has  the  horizontal  graduated  plate ;  but 
the  telescope  is  so  mounted  as  to  be  capable  of  a  complete 
revolution  in  the  vertical  plane.  The  telescope,  to  correspond 
with  the  astronomical  transit-instrument  or  transit-circle,  should 
be  supported  by  a  horizontal  axis  upon  two  standards  and  be- 
tween them.  But  an  instrument  like  Combes's  of  1836,  Figs. 
109  and  110*,  with  its  telescope  supported  only  on  one  side  like 
the  telescope  of  the  astronomical  mural  circle,  or  the  sights  of 
the  older  mural  quadrant,  has  yet  the  more  essential  quality  of 
the  transit  as  distinguished  from  the  theodolite,  namely,  the 
power  to  revolve  the  telescope  completely  in  the  vertical  plane. 
Certain  compasses,  for  example,  the  French  square  compass 
(boussole  carree),  have  such  a  side  telescope ;  but  have  still  been 
called  simply  compasses,  because  the  compass  was  their  principal 
feature  and  there  was  no  special  horizontal  graduated  plate.  To 
apply  the  name  mural,  analogous  to  transit,  would  perhaps  seem 
not  wholly  appropriate,  because  there  is  in  a  portable  instru- 
ment no  immovably  fixed  wall,  as  the  very  word  mural  implies. 
Perhaps  the  less  compact  term  side-telescope-transit  might  be 
used. 

The  expression  transit-theodolite  is  sometimes  used,  especially 
by  men  who  have  been  more  particularly  accustomed  to  the 
theodolite.  Their  idea  probably  is  that  the  distinguishing 
characteristic  of  the  theodolite  is  the  capacity  of  measuring 
both  horizontal  arid  vertical  angles.  But  the  expression  is  an 
inconvenient  or  clumsy  one,  and  the  difference  between  the 
transit  and  the  theodolite  is  so  radical  and  important  as  to 
justify  the  wholly  distinct,  simple  name  of  transit. 

Grouping. — The  different  instruments  might  perhaps  be  use- 
fully classified  in  the  manner  of  the  following  table,  beginning 
generally  with  the  simpler  and  older  forms,  and  mentioning 

*  Page  171. 


NOTES    ON    MINE-SURVEYING   INSTRUMENTS.  289 

some  of  the  principal  forms,  particularly  those  that  have  had 
special  names  given  to  them.  Instruments  that  combine  the 
features  of  more  complicated  and  simpler  forms,  as  the  theodo- 
lite and  magnetic  compass,  or  transit  and  solar  compass,  are 
well  enough  called  by  the  more  advanced  name  with  the  other 
name  prefixed;  as,  compass-theodolite,  solar-transit.  The 
name  Infallible  is  perhaps  better  suited  for  its  class  than 
Traverser ;  not  only  because  it  is  older,  but  because  traversing 
is  done  also  with  the  theodolite  and  transit. 

Classification  of  Surveying-Instruments. 

A.  Distance-measurers. 

Pole,  cord,  chain,  steel-tape,  odometer,  pedometer,  gradi- 
enter,  stadia,  barometer,  etc. 

B.  Angle-measurers. 

I.  Ungraduated  Instruments. 

Vertical  angles. 

Level. 
Horizontal  angles. 

Plane-table,  three-legged  stool. 
Without  compass. 
With  compass. 
Infallible. 

Without  compass:  Douglas's  Infallible,  1727. 
Zollmann's  Scheibe,  1781.  Henderson's 
Rapid  Traverser,  1892. 

With  compass:  Setz-compass,  1541.  Agricola's 
compass,  1556. 

II.  Graduated  Instruments. 

Quaquaversal  : 

Quadrant,  sextant,  octant. 
Vertical  angles : 

Gradbogen.     Sunflower.     Clinometer. 
Horizontal  angles  : 
Without  meridian  : 

Astrolabe.     Digges's   theodelitus,  1571.     Gen- 

sanne's  graphometre,  1770.     Eisenscheibe. 
With  meridian : 
Compass  : 


290  NOTES    ON    TRIPOD-HEADS. 

Magnetic    (including :    Hang-compass,    dial, 

circumferentor,  1796). 
Solar. 

Horizontal  and  vertical  angles : 
Without  sights  or  telescope  : 

Komarzewski's   graphometre,    1795.      Studer's 

Eisenscheibe,  1801. 
With  sights  or  telescope  : 
Theodolite : 

Without  compass  (including  Digges's  Topo- 
graphical Instrument,  1571.  Junge's  Go- 
niometer). 

With  compass  (magnetic,  or  solar,  or  both). 
Transit : 

Without  compass  (including  Combes's). 
With  compass  (magnetic,  or  solar,  or  both). 
(Including  Morin's  Combes's.) 


Notes  on  Tripod-Heads,  with  Reference  to  Mr.  Dunbar  D. 

Scott's  Paper  on  the  Evolution  of  Mine-Surveying 

Instruments. 

BY  JOHN  H.    HARDEN,   PH(ENIXVILLE,   PA. 

(Richmond  Meeting,  February,  1901.) 

IN  the  valuable  paper  of  Mr.  Dunbar  D.  Scott  and  its  varied 
discussion,  on  the  evolution  of  mine-surveying  instruments,  the 
tripod-head  has  not  received  the  attention  it  merits.  During 
the  last  50  years  this  very  necessary  adjunct  to  the  surveyor's 
instrument  has  been  much  improved.  The  legs  are  of  better 
construction ;  and  the  devices  for  laterally  moving  the  instru- 
ment over  the  station-point  and  for  quick  leveling,  without 
the  use  of  the  screws,  have  given  to  the  instrument  fitted  with 
the  modern  tripod-head  the  same  facilities  possessed  by  the  old- 
fashioned  ball-and-socket,  with  more  perfect  accuracy,  not  at- 
tainable in  the  latter,  while  saving  from  30  to  50  per  cent,  of 
the  time  required  for  setting  the  instrument  over  a  station. 

For  the  purpose  of  extending  the  discussion  to  this  import- 


NOTES    ON    TRIPOD-HEADS.  291 

ant  part  of  the  instrument,  the  subject  is  here  treated  under 
the  two  divisions  of  the  tripod-legs  and  the  tripod-head. 

Tripod-Legs. — Tripod-legs  of  wood  have  been  made  of  dif- 
ferent forms  and  cross-section,  designed  to  suit  surface  or  un- 
derground surveying  of  varied  character,  including: 

1.  The  round  leg,  of  equal  diameter  throughout  its  length, 
with  metallic  screw-joints  in  the  middle,  reducing  the  height 
of  the  instrument  one-half,  when  required,  as  in  the  leg  of  the 
"  Hedley  "  dial.     This  form  of  leg  has  no  less  than  9  joints, 
wood  and  metal  coming  together ;  it  was  never  a  firm,  cer- 
tainly not  a  durable  support,  owing  to  the  contraction  of  the 
wood  within  the  metal ;  and  the  attachment  to  the  head  gave 
an  uneven  movement  to  the  joint. 

2.  The  round  leg,  larger  in   diameter  in  the  middle  of  its 
length,  fitting  between  plates  in  the  tripod-head.    It  is  defective 
at  this  joint,  and  its  movement  is  uneven. 

3.  The  angular  section  leg  (120°),  in  which  three  legs  com- 
bined form,  when  closed,  one  compact  round  leg,  sectionally 
larger  in  the  middle  of  its  length,  very  convenient  and  easy  to 
handle.    The  joint  with  the  head  is  metallic,  insuring  a  uniform 
movement.     The  rigid  fastening  of  the  metal  to  the  wood  with 
wooden  screws  is  not  durable,  owing  to  unequal  expansion  and 
contraction  of  the  parts. 

4.  The  lattice  or  built  leg,  solid  for  a  short  part  of  the  lower 
length,  spread  to  receive  the  joint  at  the  head,  and  with  one  or 
all  legs  adjustable  to  the  height  of  the  mine  or  contour  of  the 
surface.     This,  the  modern  form  of  leg,  is  more  nearly  perfect, 
and  gives  a  firmer   support,  without  being  heavier,  than  any 
other  leg  designed.     All  its  parts  adjust  themselves  and  clamp 
together  firmly,  to  make  decidedly  the  best  form  of  tripod-leg 
for  all  classes  of  instrumental  work  in  the  field  or  mine. 

The  Tripod-Head. — The  tripod-head,  connecting  the  instru- 
ment with  the  legs,  was,  in  its  earliest  inception,  a  rigid  piece 
of  mechanism  with  ball-and-socket  or  screws  (3  or  4)  for  level- 
ing the  instrument,  after  the  legs  had  been  manipulated  to 
obtain  the  exact  position,  as  near  level  as  possible,  over  a 
station-point — an  operation  occupying  much  time  and  strategy, 
according  to  the  nature  of  the  ground. 

In  the  year  1858  Mr.  William  J.  Young,  of  Philadelphia, 
invented  an  improvement  in  tripod-heads,  known  as  the  "  shift- 
ing head."  This  was  a  decided  improvement;  for  it  enabled 

20 


292  NOTES    ON    TRIPOD-HEADS. 

the  surveyor  to  dispense,  in  a  large  degree,  with  the  process  of 
moving  or  depressing  one  or  other  of  the  legs  to  bring  the  in- 
strument over  the  station-point  exactly.  This  exactness  is  at- 
tained by  moving  the  instrument  laterally  on  the  head,  by 
means  of  the  shifting-plate,  within  the  limits  designed — usually 
about  one  inch. 

In  1877  Mr.  Daniel  Hoffman,  of  Philadelphia,  introduced 
his  improved  tripod-head,  with  a  quick-leveling  device,  together 
with  the  Young  shifting-device.  We  now  have  a  tripod-head 
with  all  facilities  for  adjusting  the  instrument  over  a  station, 
approximately  leveling  it  without  using  the  screws,  and  requir- 
ing for  the  whole  operation  from  30  to  50  per  cent,  less  time. 
The  two  devices  mentioned,  with  the  lattice-built  legs,  make  a 
tripod  fully  equal  to  the  other  parts  of  a  modern  surveying- 
instrument. 

Actual  practice  is  the  true  test.  I  have  used  these  devices 
on  all  my  instruments  during  20  years,  and  have  proved  them 
to  be  mechanically  correct  in  principle,  and  to  work  well  in 
practice.  Never  on  any  occasion  has  dust  affected  the  smooth 
working  of  the  upper  half-ball,  described  by  Mr.  Lyman ;  and 
the  tripods  made  by  Heller  &  Brightly  in  1879  are  as  perfect 
in  their  movement  as  they  were  the  day  they  left  the  hands  of 
the  maker. 

It  is  true  that  the  height  of  the  instrument  is  somewhat  in- 
creased, though  not  to  such  an  extent  as  to  destroy  its  stability, 
firmness  or  usefulness. 

It  is  also  true  that  the  approximate  parallelism  of  the  parallel 
plates  of  the  tripod  may  be  maintained,  without  such  a  device, 
by  merely  careful  setting  of  the  tripod,  with  or  without  exten- 
sible legs,  as  intimated  by  Mr.  Hoskold.  This  careful  setting 
of  the  tripod-legs,  and  the  time  required  for  doing  it,  is  what  is 
avoided  in  the  use  of  the  Hoffman  and  Young  devices,  which 
give  to  the  modern  tripod-head  its  superiority.  In  proof  of 
this,  the  devices  have  had  their  imitators ;  the  Young  shifting- 
device  having  been  imitated  by  Draper  and  others,  and  the 
Hoffman  quick-leveling  device  by  Young,  Gurley  and  others. 

In  the  suit  of  Hoffman  vs.  Young  for  infringement,  decided 
by  Judge  Butler  in  favor  of  Hoffman,  such  eminent  engineers 
as  the  late  Eckley  B.  Coxe,  Prof.  Lewis  M.  Haupt,  D.  McN. 
Stauffer,  the  late  Thomas  Shaw,  and  others,  gave  evidence  in 
favor  of  the  device  as  a  valuable  addition  to  the  tripod-head, 


THE    EVOLUTION    OF    MINE-SURVEYING    INSTRUMENTS.         293 

before  unknown  to  them.  The  Hoffman  invention,  patented  in 
England,  has  been  largely  applied  to  both  new  and  old  instru- 
ments by  John  Davis  &  Son,  Derby. 

In  conclusion,  I  may  refer  to  my  paper,  presented  to  the  In- 
stitute in  1878,  on  "  Imperfections  in  Surveying  Instruments."* 


The  Evolution  of  Mine-Surveying  Instruments. 

BY  DUNBAR  D.  SCOTT,  HOUGHTON,  MICH. 
(Concluding  Discussion. ) 

MR.  SCOTT  :  So  many  contributors  have  appeared  recently 
with  commendable  arguments  that  I  re-enter  the  field  apolo- 
getically, taking  the  liberty  first  to  supplement  Mr.  Davis's 
paper  by  showing  how  that  clever  mechanic,  Mr.  Berger,  has 
converted  the  interchangeable  auxiliary  telescope  into  a  solar 
of  the  Saegmuller  type.f 

The  auxiliary  is  made  to  revolve  about  the  polar  axis  and  in 
the  declination  circle  by  means  of  a  new  appliance  called  the 
"  equatorial  adapter,"  which  is  shown  attached  in  Fig.  164,  and 
more  in  detail  in  Fig.  165. 

It  consists  of  two  parallel  circular  plates,  the  lower  one  of 
which  is  screwed  to  the  "  vertical  pillar  "  of  the  telescope.  The 
upper  carries  the  polar  axis  with  its  peculiar  bearing-arm,  to 
which  the  auxiliary  is  attached  in  a  position  similar  to  that 
which  it  occupies  when  at  the  side  of  the  instrument.  The 
polar  axis  may  be  adjusted  to  verticality  by  means  of  a  per- 
manently attached  bubble-tube  and  two  small  thumb-screws, 
which  operate  against  springs  •  between  the  plates ;  and  the 
bearing-arm  is  governed  in  its  revolution  about  the  polar  axis 
by  the  usual  small  clamp-and-tangent  screw-arrangement. 

The  solar  adapter  with  the  small  striding  level,  used  to  bring 
the  auxiliary  back  to  a  horizontal  position  after  the  main  tele- 
scope has  been  set  for  declination,  adds  only  9  oz.  to  the 
weight  of  the  instrument,  so  that,  with  a  little  care,  the  same 
counterpoise-weight  will  answer  every  purpose. 

The  diaphragm  of  the  auxiliary,  when  thus  used  for  solar 

*  Trans.,  vii.,  308. 

f  Eng.  and  Min.  Jour.,  N.  Y.,  vol.  xlviii.,  No.  24,  Dec.  9,  1899  ;  also  Mines 
and  Minerals,  Scranton,  Pa.,  vol.  xx.,  No.  6,  Jan.,  1900. 


294        THE    EVOLUTION    OF    MINE-SURVEYING    INSTRUMENTS. 

purposes,  is  provided,  in  addition  to  the  usual  cross-webs,  with 
four  extra  coarse  webs,  forming  a  square  slightly  smaller  than 
the  sun's  image,  as  shown  in  Fig.  166.  This  arrangement  of 
webs,  as  Mr.  Ljman  will  see,  does  not  interfere  with  the  suc- 
cessful operation  of  the  auxiliary  in  mining  work ;  and,  indeed, 
there  is  no  valid  objection  to  the  use  of  cross-webs — though, 

FIG.  164. 


The  Interchangeable  Auxiliary  Telescope  Adapted  to  Solar  Work. 

for  the  peculiar  exigencies  encountered  in  conducting  a  mine- 
survey  with  an  interchangeable  auxiliary,  a  single  web  fulfills 
every  demand  and  is  not  a  "  serious  inconvenience,"  unless  the 
surveyor  insists  upon  doing  the  very  thing  I  am  trying  to 
avoid,  namely,  observing  vertical  angles  with  the  auxiliary  on 
top,  and  computing  the  correction  for  eccentricity. 


THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS.          295 

Mr.  Lyman  is  entitled  to  grateful  acknowledgment  for  the 
very  thorough  investigation  he  has  made  in  response  to  the 
last  paragraph  of  my  paper,*  which  was  intended  to  convey 
more  plainly  my  own  estimate  of  its  worth  than  the  presump- 
tuous title  would  imply.  The  time  available  for  its  preparation 
in  the  midst  of  a  busy  professional  career  was  so  limited  as  to 
permit  errors  and  misconceptions  to  creep  in.  Of  course  it  is 
as  absurd  to  suppose  that  Ramsden  had  constructed  his  circular 
dividing  engine  at  twenty-three,  in  the  second  year  of  his  ap- 
prenticeship, as  that  Draper  had  constructed  a  transit  in  the 
sixteenth  year  of  his  age  ;  and  the  implied  assertion  that  Rams- 
den  had  introduced,  posthumously,  a  transit-principle  is  a  self- 
evident  mistake,  f 

Mr.   Hoskold  has    shown  in   his   second   contribution  that 

FIG.  165. 

FIG.  166. 


Diaphragm  of  the  Interchangeable 
Solar  Auxiliary. 


The  Solar  Adapter. 


Ramsden  did  not  complete  his  dividing-engine  until  1773,  in- 
stead of  1760,  as  I  had  it ;  J  and  while  no  less  an  authority  than 
Mr.  Stanley  is  responsible  for  the  citation  concerning  the  in- 
troduction of  the  transit-principle  by  Ramsden  in  1803,§  he 
is  now  unwilling  to  substantiate  any  part  of  it,  and,  in  writing 
me,  seems  inclined  to  forgive  us  for  having  detected  an  inac- 
curacy in  his  otherwise  studiously  prepared  and  exhaustive 
work. 

*  SECRETARY'S  NOTE. — The  paragraph  here  referred  to,  which  formed  the  con- 
clusion of  Mr.  Scott's  paper  in  its  pamphlet  form,  was  a  request  for  correspon- 
dence, corrections,  and  additional  facts.  Having  served  its  purpose,  it  was,  for 
obvious  reasons,  and  in  accordance  with  usual  practice,  omitted  when  the  paper 
was  printed  in  permanent  form  in  vol.  xxviii. — K.  W.  K. 

f  Mr.  Lyman's  paper,  Canadian  meeting,  Aug.,  1900,  pamphlet  ed.,  pp.  33-35. 

j  Trans.,  xxviii.,  694  and  697. 

$  Surveying  Instruments,  William  Ford  Stanley,  2d  ed. ,  London,  1895,  p.  206. 


296        THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS. 

Much  force  was  given,  in  my  mind,  to  this  citation,  when  I 
found  in  Adams's  Geometrical  Essays,  published  six  years  previ- 
ously (1797),  a  description  and  cut  of  a  miniature  theodolite, 
herewith  reproduced  in  Fig.  167.  This  is  a  4-inch  model  which 
Adams  designed  in  1791,  and  at  least  suggests  the  possibility 
of  making  a  small  transit-instrument  by  slightly  increasing  the 
height  of  the  standards  as  they  occur  in  the  contemporaneous 
instrument  shown  in  Fig.  16,  and  by  substituting  a  better- 
proportioned  telescope. 

FIG.  167. 


Adams's  Miniature  Theodolite. 

The  telescope  rested  in  a  sort  of  cradle,  and  could  be  re- 
versed, end  for  end,  by  opening  the  clips,  a,  a.  The  vertical 
arc  was  set  concentric  with  the  axis  of  revolution ;  and  while, 
by  the  old-fashioned  rack-and-pinion  screw,  the  telescope  could 
be  made  to  move  through  an  arc  of  only  from  30°  to  40°  above 
and  below  the  horizon,  I  consider  this,  in  some  respects,  the 
most  perfect  of  old  English  portable  instruments. 

Dr.  Raymond  has  called  attention  to  the  fact  that  the  original 
astronomical  transit-instrument  was  the  invention  of  Roemer 
(Olaus  Roemer,  the  Danish  astronomer)  in  1700,  though  other 


THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS. 


297 


FIG.  168. 


authorities  place  the  date  as  early  as  1689 ;  for  the  instrument 
was  described  in  1700  in  the  third  volume  of  Miscellanea  Bero- 
linensia.  In  1704  Roemer  combined  with  it  a  vertical  or  alti- 
tude-circle, possibly  the  first  of  that  type  of  instrument  which 
the  English  have  since  designated  "  alt-azimuth." 

The  first  of  this  class  for  the  Greenwich  observatory  was 
built  by  Troughton  in  1816 ;  and  Mr.  W.  T.  Lynn*  informs  me 
that  the  first  of  the  portable 
type,  to  the  best  of  his  knowl- 
edge, is  referred  to  in  the  sixth 
volume  of  the  edition  of  1830 
of  the  Edinburgh  Cyclopedia, 
where  there  is  illustrated  and 
described  a  portable  transit- 
instrument  which  Edward 
Troughton  designed  in  1810. 
In  the  same  place  he  is  credited 
with  having  contrived  a  similar 
one  as  far  back  as  1792. 

Later,  Mr.  Lynn  says,  there 
was  published  in  the  Dictionary 
of  Arts,  Sciences  and  Literature 
(Abram  Rees,  1810)  another 
model  of  Troughton's,  which 
bears  a  very  close  resemblance 
to  Young's.  The  only  copy  of 
this  rare  work  known  to  Mr. 
Lynn  is  preserved  in  the  British 
Museum,  where  they  object  to 
having  reproductions  of  any 
kind  made,  though  I  hope  sub- 
sequently to  prevail  upon  the 

Director  to  extend  this  courtesy  to  American  students.  The 
transit  illustrated  by  Rees  has  some  points  in  common  with  the 
one  I  have  selected  from  Simms's  workf  and  presented  in  Fig. 
168.  The  author  does  not  give  the  date  of  its  introduction; 

*  Late  of  the  Koyal  Observatory ;  now  residing  at  26  South  Vale,  Black- 
heath,  London,  S.E. 

f  A  Treatise  on  Mathematical  Instruments,  F.  W.  Simms,  London  ;  1st  ed. ,  1834  ; 
5th,  1844. 


8-inch  Alt-Azimuth. 


298        THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS. 

but  Mr.  "W.  Simms  (now  retired  from  the  firm  of  Troughton  & 
Simms)  testifies  that  it  was  a  regular  model  when  he  entered 
the  business  in  1832.  The  azimuth-axis  of  this  transit-instru- 
ment was  inverted  between  the  standards,  as  in  one  of  Mr. 
Hoskold's  instruments ;  but  the  pillars  were  of  sufficient  height 
to  permit  a  complete  revolution  of  the  telescope — a  desirable 
feature  not  included  in  the  model  just  referred  to  (Fig.  75, 
p.  99). 

It  would  be  hardly  fair,  from  what  I  know  at  this  writing 
concerning  these  instruments,  to  attempt  to  show  that  the  de- 
signs prevalent  in  early  English  models  were  in  any  way  re- 
sponsible for  that  of  Young,  particularly  as  these  so-called 
altitude-  and  azimuth-instruments,  with  their  large  circles  and 
reading-microscopes,  were  intended  rather  for  geodetic  work 
than  for  civil  or  railroad-engineering.  It  is  noteworthy  that, 
in  another  work  of  Simms,*  one  E.  M.  Clark  advertises  to  sell 
"  Young's  Railway  Transit,"  and  recommends  it  as  possessing 
many  advantages  over  the  theodolite  for  railroad  work. 

My  remarks  upon  Young's  invention  were,  in  a  measure, 
based  upon  a  long-established  popular  opinion,  sustained  by 
such  authorities,  among  others,  as  Johnsonf  and  Carhart.J  I 
do  not  think  the  elder  Young  would  claim  what  was  not  right- 
fully his.  His  grandson,  in  contributing  to  this  discussion, 
has  been  noticeably  generous  in  the  apportionment  of  honors 
with  a  fine  sense  of  charity  unknown  to  some  of  the  phenome- 
nal manufacturing  inventors  who  sit  in  their  shops  and  antici- 
pate the  instrumental  embodiment  of  every  scientific  principle 
with  which  the  engineering  profession  has  to  deal ! 

Mr.  Lyman's  researches  concerning  Draper  are  highly  appre- 
ciated ;  but  any  attempt  to  associate  his  name  with  the  inven- 
tion and  introduction  of  the  transit  in  America  seems  to  be 
permanently  defeated  'by  the  evidence  of  Mr.  B.  Jay  Antrim, 
Draper's  oldest  apprentice,  still  residing  in  Philadelphia,  who 
testifies  that  he  was  born  in  1819,  and,  at  the  age  of  15,  went 
to  learn  his  trade  of  Draper,  who,  at  that  time,  had  been  in 
business  two  years.  If  Mr.  Antrim's  recollection  be  accurate, 

*  A  Treatise  on  Drawing  Instruments,  F.  W.  Simms,  London,  3d  ed.,  1847. 
f  Theory  and  Practice  of  Surveying,  J.    B.   Johnson,   C.E.,   New  York,   1886, 
1889,  p.  86. 

I  A  Treatise  on  Plane- Surveying,  Daniel  Carhart,  C.E.,  Boston,  1887-93,  p.  396. 


THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS.          299 

Young's  transit,  as  shown  in  Fig.  60,  was  on  the  market  a  year 
before  Draper  became  established ;  and  it  would  further  appear 
that,  where  I  have  spoken  of  Draper's  house  as  founded  in 
1815,*  I  am  in  error,  as  well  as  my  informant,  Mr.  Knight,  by 
about  17  years. 

Mr.  Lyman's  heroism  in  the  defence  of  Mr.  Heller  (p.  281) 
is  characteristic  and  commendable ;  but  I  do  not  deserve  the 
imputation  of  being  partial  or  malicious.  I  made  repeated 
efforts  to  obtain  information  from  Mr.  Heller  in  correspond- 
ence, and  even  went  to  the  patient  expedient  of  inducing  an 
acquaintance  to  call  at  his  office  for  that  purpose,  but  was  not, 
I  regret  to  say,  indulged  with  the  solicited  consideration.  If, 
however,  after  the  lapse  of  two  years,  he  has  delivered  the  de- 
sired facts  to  Mr.  Lyman,  I  am  obliged  to  both  for  thus  enrich- 
ing the  technical  value  of  this  investigation. 

At  first  glance,  Figs.  159  and  160  in  Mr.  Lyman's  paper 
seem  to  contradict  my  somewhat  sweeping  statement  at  the 
top  of  p.  40 ;  but  it  appears  that  the  small  structures  at  the 
side  of  the  pillars  are  not  intended  for  the  adjustment  of  paral- 
lelism, being  only  clamping-screws,  with  unusually  long  shanks, 
into  which  are  inserted  "  safety-pins "  to  prevent  loss.  My 
statement  is  none  the  less  to  be  qualified  by  the  fact  that  the 
first  side-auxiliary  which  Heller  &  Brightly  introduced  in  1871 
was  capable  of  being  tested  for  parallelism  by  four  clamping- 
and  four  adjusting-screws,  in  much  the  same  manner,  I  un- 
derstand, as  that  adopted  by  Saegmuller  in  1881  for  his  solar 
attachment. 

Perhaps  that  statement  ought  to  be  further  corrected  by  a 
claim  of  the  F.  E.  Brandis,  Sons  &  Co.,f  who  introduced  in 
1890  the  instrument  shown  in  Fig.  169. 

The  top-telescope  of  this  instrument  was  attached  to  the 
main  telescope  by  the  usual  small  upright  pillars  and  locking- 
nuts;  but  in  addition  to  these  there  was  supplied  a  round 
capstan-screw  base,  intended  to  either  increase  or  diminish 
slightly  the  length  of  the  pillars,  and  so  to  adjust  the  tele- 
scopes for  parallelism.  The  position  of  the  hubs,  as  fixed  by 
the  makers,  was  supposed  always  to  insure  the  adjustment  for 

*  Trans.,  xxviii.,  704. 

f  Mathematical  instrument-makers,  814  Gates  Ave. ,  Brooklyn,  N.  Y. 


FIG.  169. 


300        THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS. 

alignment;  but  later,  in  1894,  they  made  it  possible  to  test 
this  by  mounting  the  pillars  on  annular  straps,  which  were 
movable  in  azimuth. 

In  1891  this  firm  made  also,  upon  the  order  of  Barry  Searle, 

E.M.,  then  of  Montrose,Pa., 
an  instrument  which  he  in- 
tended should  meet  all  the 
requirements  of  solar,  min- 
ing and  railroad-work.  In 
a  letter  to  me,  Mr.  Searle 
describes  it  as  provided  with 
a  detachable  side-telescope 
and  a  Saegmuller  solar  at- 
tachment. The  side-tele- 
scope was  provided  with  a 
small  longitudinal  bubble, 
according  to  the  practice  in- 
stituted by  the  Brandis  Co. 
in  1888  for  the  purpose  of 
insuring  a  correct  replace- 
ment of  the  auxiliary  to  cor- 
respond with  the  zero  of  the 
vertical  circle.  Mr.  Searle's 
instrument  was  furnished 
with  an  adjustable  120°  ver- 
tical arc,  similar  to  that  in 
Fig.  169,  together  with  a 
prismatic  eye-piece  and 
stadia-wires.  In  my  origi- 
nal paper*  I  quoted  from 
Prof.  Baker  the  statement 
that  "  stadia-hairs  were  not 

introduced  in  America  until  after  the  Civil  War."  This  is 
incorrect,  as  the  following  passage  from  an  American  author 
shows : 

"The  credit  of  having  first  introduced  this  method  of  measurement  in  this 
country  would  seem  to  belong  to  Mr.  John  B.  Mayer,  a  French-Swiss.  It  was  used 
by  him  as  early  as  1850,  and  subsequently  during  his  connection  with  the  U.  S. 


Brandis  Mine  Transit. 


Trans.,  xxviii.,  721. 


THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS.          301 

Lake  Survey.  ...  An  essay  by  him  in  the  Journal  of  the  Franklin  Institute,  Jan., 
1865,  contains  a  short  historical  sketch  of  the  development  of  topographical  sur- 
veying, and  a  brief  discussion  of  the  principles  of  stadia-measurement."* 

I  am  not,  nor  does  Mr.  Lyman  seem  to  be,  convinced  by  any 
evidence  yet  developed  that  the  micrometer  of  Gascoigne  in- 
volved the  principle  of  stretching  hairs  or  filaments  across  the 
diaphragm,  as  used  by  Watt  (1771)  and  Green  (1778).  Town- 
ley  says  nothing  of  hairs  in  mentioning  Gascoigne's  microme- 
ter ;  and  the  citation  from  Mackenzie,  even  if  it  may  be  con- 
sidered as  authoritative,  is  not  sufficient  to  prove  this  point. 
Mr.  Lyman  writes  me  that  Grant,  in  his  History  of  Physical 
Astronomy,  says,  at  p.  452  : 

"  Mr.  Townley's  micrometer  was  actually  produced  before  the  meeting  held  on 
the  25th  of  July,  1667  ;  and  a  detailed  description  of  it  was  subsequently  given 
in  No.  29  of  the  Phttos.  Trans.  In  principle  it  exactly  resembles  the  micrometer 
of  Auzout.  Two  straight  edges  of  metal  are  made  to  approach  each  other  at  the 
focus  of  the  telescope  by  means  of  a  screw,  the  mechanism  being  so  contrived 
that  the  optical  axis  of  the  telescope  is  always  situate  midway  between  the  two 
edges Hooke  suggested  an  improvement  upon  this  micrometer  by  substi- 
tuting human  hairs  for  the  solid  edges." 

My  observation  at  the  top  of  p.  43  has  yet,  I  believe,  to  be 
disproved,  even  though,  at  the  time,  I  had  overlooked  James 
"Watt.  More  recently  there  has  come  to  my  notice  other  litera- 
ture on  the  subject,f  introducing  a  new  claimant  who,  with  re- 
spect to  the  stadiametric  principle,  will  at  least  supersede  both 
"Watt  and  Green.  At  p.  619  of  his  work  on  surveying,!  Dr. 
Jordan  says,  as  one  would  translate  : 

"Concerning  the  history  of  the  stadia,  it  is  reported  in  Etudes  theoriques  et 
pratiques  sur  les  levers  topometriques  et  sur  tacheometrie,  by  C.  M.  Goulier,  Paris,  1 892, 
that  the  stadiametric  measurement  was  commonly  supposed  to  have  been  invented 
in  1778,  by  Wm.  Green,  an  optician  of  London,  and  has  been  used  since  1812,  in 
Holland,  by  French  army  officers,  and  since  1816  in  mapping  the  borders  of 
Savoy.  The  Italians  date  the  invention  still  further  back  to  1674,  at  which  date 
Geminiano  Montanari  introduced  the  practice  of  placing  upon  the  diaphragm 
many  equidistant  threads  ;  and  the  number  of  these  intervals,  for  a  rod  of  a  fixed 
length,  determined  the  distance  at  which  it  was  placed.  As  an  authority  for 

*  Stadia- Survey  ing,  Arthur  Winslow,  New  York,  1884,  p.  5. 

f  Prof.  E.  Hammer  in  Zeitschrift  fur  Vermessungswesen,  xx.  Band,  Heft  11,  1891; 
also,  the  same  with  addenda  in  Zeit.  fur  Instrumentenkunde,  May,  1892.  See  also 
Prof.  M.  Schmidt  on  "  Mensula  Prsetoriana,"  in  Zeit.  fur  Verm.,  xxii.  Band, 
Heft  9,  1893. 

J  Handbuch  der  Vermessungskunde,  Dr.  W.  Jordan,  Stuttgart,  5th  ed.,  1897. 


302        THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS. 

these  facts  is  cited  La  livella  diottrica  of  Dr.  G.  Montanari,  Venezia,  1680,  p.  28 ; 
and  one  should  also  compare  Instrument  e  metodi  moderni  di  geometria  applicata,  A. 
Salmoiraghi,  Milano,  1884,  pp.  278-279." 

The  conception  of  the  idea  of  subtense  measurement,  with  a 
constant  length  of  rod,  plainly  belongs,  then,  to  Montanari, 
while  Watt  and  Green  seem  entitled  to  only  the  credit  of  hav- 
ing introduced  the  improved  method  as  we  use  it  to-day. 

I  am  reminded  here  to  touch  briefly  upon  the  subject  of 
platinum  wires.  While  I  have  no  authority  or  inclination  to 
dispute  the  fact  that  Heller  &  Brightly  were  first  to  introduce 
these  in  America,  their  original  introduction  as  a  substitute  for 
spider-webs  on  the  diaphragms  of  telescopes  certainly  belongs 
to  Dr.  Wm.  Hyde  Wollaston,  a  celebrated  English  scientist, 
who  died  in  1828.  He  received  a  medal  of  the  Royal  Society 
for  his  process  of  manufacturing  platinum ;  and  his  paper  on 
its  malleability  was  published  in  the  Philos.  Trans,  the  year 
following  his  death.  It  is  now  hinted  that  he  acquired  the 
secret  of  rendering  it  malleable  from  one  Thomas  Cock. 

Because  Digges  incidentally  recommended  his  theodelitus  for 
use  in  mines  in  a  short  note,  in  which  his  only  instructions  are 
to  the  effect  that  "  the  diligent  practizioner  shall  be  able  of 
himselfe  to  invent  manifolde  meanes  to  resolve  "  the  problems 
confronting  him,  Dr.  Raymond  omits  to  give  v.  Hanstadt  the 
credit  of  having  written  the  first  exclusive  treatise  011  mine- 
surveying,  in  which  the  theodolite  is  recommended  in  prefer- 
ence to  all  other  instruments. 

At  any  rate,  with  respect  to  the  hollow  brass  cylinders 
spoken  of,  I  feel  impelled  to  take  exception  to  the  foot-note  at 
the  bottom  of  p.  169,  in  the  course  of  Dr.  Raymond's  remarks, 
as  confusing.  While  the  Spreitzen  or  gang-plank  is  the  same 
in  each  case,  the  methods  of  setting-up  are  very  different; 
and  to  distinguish  these  features  I  submit  a  cut  of  Mohling's 
Msenscheibe  and  its  support  (Fig.  170),  with  a  few  extracts  taken 
from  his  work.* 

' '  The  Eisenscheibe  differs  from  the  astrolabe  only  that  it  is  provided  with  a 
ball-and-socket  joint  beneath  the  center,  and,  in  place  of  the  diopters,  is  supplied 
with  two  similarly  constructed  lineals,  having  hooks  at  the  outer  ends  and  pivot- 
joints  at  the  center. 

*  Anleitung  zur  Markscheidekunst,  Johann  Mohling,  Wien,  1793,  p.  155. 


THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS.          303 

"  In  the  beginning  of  a  survey  the  Kreutzschraube  (cross-screw)  is  set  firmly  into 
the  plank  of  the  second  station.  After  the  shank  of  the  instrument  has  been  in- 
serted into  the  socket  of  the  support,  one  of  the  arms  is  connected  by  a  cord  with 
the  first  station,  and  the  instrument  is  swung  upon  its  axis  until  the  zero  of  the 
graduations  coincides  with  the  index  of  this  arm.  The  second  arm  is  now  con- 
nected with  a  cross-screw  placed  at  the  third  station  in  the  same  manner  ;  and  the 
indicated  angle  on  the  plate  is  the  one  sought. 

"  The  inclination  of  the  cord  is  determined  by  the  Gradbogen,  and  the  distance 
by  measurement,  in  the  usual  way. 

tl  Because  the  instrument  must  sit  very  securely,  on  account  of  the  tension  in 
the  cords,  we  cannot  use  a  tripod,  as  with  the  astrolabe,  so  that  a  very  solidly 
wedged  plank  is  necessary,  and  this  is  especially  true  since  one  must  be  certain 
of  placing  the  instrument  precisely  at  the  point  to  which  the  cord  had  been  pre- 
viously stretched." 

FIG.  170. 


Mohling's  Eisenscheibe  and  Support. 


So  far  as  I  know,  Mohling's  form  of  support  is  unique ;  but 
the  Spreitzen  method  of  setting-up  is  very  old,  and  probably 
dates  back  to  the  time  when  the  astrolabe  was  first  employed 
in  mines.  Another  application  of  it  (Fig.  172),  in  which  no 
holes  are  bored,  I  shall  include  in  the  short  discussion  on  the 
plummet-lamp  of  Mr.  Coxe,  which  I  now  beg  leave  to  submit. 

The  plummet-lamp,  as  introduced  in  America  by  that  versa- 
tile engineer,  Mr.  Eckley  B.  Coxe,  I  infer,  was  the  more  highly 
civilized  resultant  of  an  old  German  method,  taught  him  while 
he  was  a  student  at  Freiberg. 

Weisbach's  hanging  lamp,  reproduced  here  in  the  first  part 
of  Fig.  171,  is  selected  from  his  work  of  1859 ;  and  I  have  no 
doubt  that,  being  his  invention,  it  also  occurs  in  the  first  edition 
(1851).  Its  construction  is  so  apparent  that  no  special  explan- 
ation need  be  given. 


304        THE    EVOLUTION    OF    MINE-SURVEYING    INSTRUMENTS. 


He  recommended  it  for  surveys  where,  in  open  chambers 
and  the  like,  the  instrument  had  to  be  mounted  upon  a  tripod, 
except  for  sights  of  less  than  3  Lachter  (fathoms).  In  that  case, 
he  explains,  an  attempt  to  bisect  the  flame  is  not  attended  with 


FIG.  171. 


Weisbach.  Coxe. 

The  Hanging  Lamps  of  Weisbach,  1850,  and  Coxe,  1870. 

good  results ;  and  in  such  cases  the  plumb-line  only  should  be 
sighted. 

Weisbach  always  greatly  preferred  the  Spreitzen  method  of 
setting-up,  as  shown  again  in  Fig.  172,  and  the  Setz-signal-lampe 


THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS. 


305 


(Fig.  173),  which,  as  he  contrived  it,  was,  in  reality,  the  base 
of  a  theodolite  peculiarly  designed  to  carry  out  this  practice. 
His  special  argument  in  favor  of  the  Spreitzen  system  was 
based  on  the  fact  that  the  plank  provided  room,  not  only  for 
the  instrument,  but  also  for  the  hand-lamp  and  the  note-book, 
as  occasion  demanded. 

The  Setzlampe  was    a   brass  plate  with    a   central   circular 

FIG.  172. 


A/; 


Weisbach's  Spreitzen  and  Setzlampe  System. 

socket,  into  which  the  box-bubble  was  first  placed,  and  then, 
when  the  plate  was  perfectly  level,  the  oil-cup  and  burner.  To 
insure  a  permanent  adjustment  in  this  respect,  the  small  nuts 
on  the  upper  shank  of  the  leveling-screws  were  screwed  down 
tightly  against  the  plate. 

When  a  sight  had  been  taken  upon  the  flame,  the  lamp  was 
removed,  the  instrument  was  brought  forward,  and  the  legs 
were  clamped  into  the  saddles,  B,  B,  by  the  little  set-screws  at 


306         THE    EVOLUTION    OF    MINE-SURVEYING   INSTRUMENTS. 


the  side.     The  circular  base  of  the  theodolite  was  also   de- 
signed to  fit  perfectly  into  the  lamp-cavity  of  the  plate. 

This  is  another  instance  of  the  three-screw  leveling-method. 
Not  feeling  competent,  I  shall  not  attempt  to  discuss  that  point 
further,  but  will  rather  leave  the  exposition  of  its  merits  to  Mr. 
Stanley,  who  I  trust  will  favor  us  eventually  with  a  more  ex- 
tensive account  of  his  research  in  England  and  on  the  conti- 
nent of  Europe.  In  1870 
Stanley  introduced  a  special 
form  of  theodolite,  intended 
to  be  universal  in  its  appli- 
cation, which  he  termed  the 
geodolite ;  but  for  mining 
work  it  was  much  too  tall 

FIG.  173. 


FIG.  174. 


Weisbach's  Setzlampe. 


Stanley's  Nadir  Mining  and  Eailroad 
Tunnel  Theodolite. 


and  weak,  so  that  the  model  was  abandoned.  Eecently  he  has 
come  out  with  something  novel  in  the  way  of  a  nadir  mining 
theodolite,  shown  in  Fig.  174,  which  invites  special  attention 
to  the  three-screw  argument,  as  well  as  the  shifting  center 
in  connection  with  this  construction. 

In  the  Stanley  4-in.  model  (Fig.  174),  the  outside  diameter 
of  the  vertical  axis  is  2f  in.,  the  clear  central  aperture  2|  in., 
and  the  range  of  the  telescope  on  each  side  of  the  nadir  5°. 
The  distances  between  the  leveling-screws  mark  a  triangle  of 


THE    EVOLUTION    OF    MINE-SURVEYING    INSTRUMENTS.          307 

6|  in.  on  a  side,  and  the  entire  weight  of  the  instrument  alone 
is  16  Ibs.  The  horizontal  axis  of  this  instrument  is  pierced  to 
permit  the  diaphragm  to  be  illuminated  by  a  bracket-lamp ; 
but  I  regard  such  lamps  as  abominable  excrescences,  and  the 
perforation  of  the  horizontal  axis  as  a  reckless  novelty,  for  min- 
ing work.  The  damp  atmosphere  of  a  mine  should  never  be 
allowed  to  enter  a  telescope  in  this  way,  to  film  the  lenses  with 
moisture  and  relax  the  spider-webs  by  virtue  of  their  hygro- 
metric  properties.  Even  an  objective  reflector  is  unnecessary; 
for  by  simply  flickering  the  candle-flame  a  short  distance  in 
front  of  the  objective,  one  can  sufficiently  discern  the  cross-webs 
until  he  gets  them  bearing  on  an  illuminated  plumb-line  or 
station. 

Concerning  my  own  instrument,  again  I  refrain  from  ex- 
tended discussion.  I  have,  perhaps  pardonably,  elevated  it  to 
lofty  dignity  among  other  mining  instruments,  because  it  em- 
braces everything  that  I  consider  essential  for  accuracy,  sim- 
plicity, rapidity  and  completeness.  That,  however,  is  a  purely 
personal  opinion.  Others,  after  studying  its  features,  will  ac- 
cept or  reject  it  as  they  choose.  I  have  absolutely  no  pecuniary 
interest  in  inciting  enthusiasm  anywhere. 

It  is  not  improbable  that  this  general  topic  will  be  pursued 
indefinitely  by  other  members  and  outsiders,  and  even  I  may 
ask  permission  to  appear  again ;  but,  before  I  finish  this  contri- 
bution, I  wish  to  make  ample  acknowledgment  of  my  grati- 
tude for  the  valuable  assistance  furnished  me  by  the  many 
gentlemen  who  have  given  up  their  time  at  my  peremptory  de- 
mand. To  make  special  mention  of  a  few  would  be  an  injustice 
to  the  rest,  and  to  enumerate  all,  an  imposition  upon  the  space 
available  in  these  Transactions ;  but  I  hope  each  may  feel  him- 
self repaid  by  the  result  of  the  labors  of  all,  and  that  the  infor- 
mation thus  collected  may  be  of  service  to  mining  students 
now  and  hereafter. 


21 


INDEX. 


[Note.— In  this  Index  the  names  of  the  authors  are  printed  in  SMALL  CAPITALS, 
and  the  titles  of  papers  in  italics.  Casual  references,  giving  but  little  information,  are 
usually  indicated  by  bracketed  page  numbers.] 


Accuracy  of:  mine  surveying,  76,  236  ;  surveying  with  the  chain  tape,  285;  telescopic 
sighting  down  a  shaft,  149 ;  the  compass,  55,  64,  221,  244  ;  the  mine  theodolite,  236. 

Achromatic  lens :  first  made  by  Chester  Moor  Hall,  261 ;  patented  by  Dollond,  261. 

Achromatic  object-glass,  fluid  :  contrived  by  Blair,  261;  practically  useless,  262. 

Adams:  his  dial,  15;  miniature  theodolite,  296;  on  surveyor's  need  of  adjusting  sur- 
veying instruments,  34. 

Adapter,  equatorial,  or  solar,  Berger's,  293. 

Adjusting  the  surveying-transit  telescope,  two  methods,  269. 

Adrianzoon,  Jacob  (also  called  James  Metius),  later  invented  refracting  telescope, 
255. 

Aerial  telescope,  261. 

Agricola,  Georgius:  De  Re  Metallica,  1;  his  compass,  classified  place,  289;  on  the  di- 
vining-rod, 3. 

Albrecht,  surveying-instrument  of  1673,  235. 

Alexander  de  Spina,  Friar,  first  published  spectacles,  247. 

Alfarabius  credits  Egypt  with  invention  of  surveying,  238. 

Alhazen  on  optics,  245. 

Alhidada,  263. 

Alt-azimuth :  Roemer's,  297 ;  Troughton's,  297. 

Aluminum  unsuitable  for  surveying-instruments,  286. 

American:  first  transit,  25,  66,  67;  wonder  at  English  adherence  to  the  theodolite, 
19. 

Ancient:  astronomical  instruments,  92  ;  history  of  surveying  instruments,  91. 

Angle-measurers  as  a  class,  289. 

Angleometer,  Hoskold's,  30,  31,  236. 

Antoninus  apparently  did  not  use  angular  instruments,  93. 

Archimedes's  ship-burning,  246,  252,  253. 

Arc-measuring  to  one  second  with  Hoskold's  micrometer-microscope,  115. 

Aristophanes's  knowledge  of  the  burning-glass,  246. 

Assyrian  :  astrolabe,  circular,  92 ;  surveying,  92. 

Astrolabe  (Astrolabium) :  and  cross-staff  described  by  Mayer,  122;  application  of  the 
name,  287;  classified  place,  289;  definition  of,  166  ;  early  use,  94,  95;  predecessor 
of  the  modern  mine-theodolite,  12. 

Astronomical  method  of  connecting  surface-  and  underground-surveys,  33. 

Auxiliary  side-telescope:  Heller  &  Brightly's,  280 ;  in  English  mine-surveying,  31; 
on  vertical  circle,  35. 

Auxiliary  telescope  below,  101  et  seq. 

Auxiliary  top-telescope,  Heller  &  Brightly's,  280. 

Babylonian:  mapping,  238;  map-tablet,  239. 

Bacon,  Friar  Roger :  his  book  helped  Digges,  7,  255 ;  supposed  invention  of  the  tele- 
scope, 7,  245  et  seq. 


310  INDEX. 

Baker,  Thomas :  method  of  connecting  surface-  and  underground-surveys,  33 ;  on 
solar  compasses,  43. 

Bartelot's  (Dr.)  mining  compass,  154. 

Batterman's  (E.  M.)  transit,  49,  50. 

Beanlands,  Arthur:  astronomical  method  of  connecting  surface-  and  underground- 
surveys,  33 ;  perfected  system  of  connecting  surface-lines  and  underground 
workings,  110. 

Bell-Elliott-Eckhold  omnimeter,  191. 

BERGEB,  C.  L.  AND  SONS  :  remarks  in  discussion  of  Mr.  Scott's  paper  on  the  evolution 
of  mine-surveying  instruments,  77. 

Berger's  (C.  L.) :  nadir-instrument  designed  for  G.  H.  Crafts,  77 ;  conversion  of 
Scott's  interchangeable  auxiliary  telescope  into  a  solar,  293 ;  diaphragm,  293, 
295. 

Beveled-edge  graduation,  113 ;  compared  with  flat,  272. 

Beyer  on  the  divining-rod,  4. 

Bion's  circumferentor,  219. 

Blair  (Dr.)  contrived  fluid  achromatic  object-glass,  261 ;  improved  objectives  [19]. 

Blattner's  (Henry)  transit  with  hinged  standards,  48,  49. 

Borchers'  (E.):  eccentric  instrument  26,  27,  34;  theodolites,  82. 

Borda'  introduced  the  method  of  repetition  of  observed  arcs,  50. 

Bourns :  method  of  connecting  underground-  and  surface-surveys,  34 ;  probably 
first  used  modern  English  theodolite  for  connecting  underground-  and  surface- 
surveys,  20 ;  use  of  portable  transit-instrument  for  producing  a  surface-line  un- 
derground, 109. 

Boussole  carree :  [242] ;  application  of  the  name,  288. 

Box  tunnel  survey  with  portable  transit-instrument,  109. 

Bracket-lamp  to  light  cross-hairs,  307. 

Brandis,  Sons  &  Co.,  F.  E. :  mine  transit,  299 ;  nadir-instrument,  23 ;  solar  transit, 
191. 

Brathuhn  (Prof.):  his  immovable  scale  in  diaphragm,  58;  on  early  stationary  com- 
pass, 4, 

BREITHAUPT,  F.  W.  UNO  SOHN  :  remarks  in  discussion  of  Mr.  Scott's  paper  on  the 
evolution  of  mine-surveying  instruments,  78;  eccentric  mine-theodolite,  or  tran- 
sit, 18,  80 ;  mine-theodolite,  American  pattern,  59  ;  modern  mine-theodolite,  38 ; 
orientation  instrument,  54,  55;  pocket  mine-theodolite,  30. 

Breithaupt's  (H.  C.  W.)  mine-theodolite  of  1798,  15. 

Broken-telescope:  defined,  86;  invented,  86;  one  of  the  oldest  known,  83. 

Bronze,  cast,  first  used  for  transits  in  1871,  by  Heller  &  Brightly,  276. 

BROUGH,  BENNETT  H. :  remarks  in  discussion  of  Mr.  Scott's  paper  on  the  evolution 
of  mine-surveying  instruments,  68 ;  on  declination  of  the  magnetic  needle,  11. 

BRUNTON,  D.  W. :  remarks  in  discussion  of  Mr.  Scott's  paper  on  the  evolution  of 
mine-surveying  instruments,  88 ;  pocket-transit,  89  et  seq. 

Buddhist  early  astronomical  instruments,  92. 

Buff  &  Berger :  against  aluminum  for  surveying  instruments,  286 ;  detachable 
ball-and-socket  quick-leveling  tripod-head,  57 ;  duplex-bearing  mine-transit,  56  ; 
Pearson's  solar  attachment,  183 ;  shaft-transit,  23 ;  solar  attachment,  184 ;  top- 
telescope  with  adjustable  trivet,  60. 

Burt's  (William)  solar  compass,  43,  47, 175. 

Cairo  astrolabe  of  1240,  95. 

Casella's  (Louis):  miner's  dial  with  telemeter,  41;  portable  theodolite,  30;  travelers' 

small  side-telescope  theodolite,  104. 
Catageolabium,  Giuliani's,  16,  82,  86. 
Cater's  (Henry)  prismatic-compass  dial,  46. 

Center,  compound,  made  feasible  for  ordinary  transits  by  Heller  &  Brightly,  277. 
Centesimal  graduation,  29 ;  by  Young,  29. 


INDEX.  311 

Chain:  and  tape,  283;  classified  place,  289;  Gunter's,  284;  in  use  underground,  121; 
Eittenhouse's,  283 ;  steel  standard,  underground,  216 ;  -tape,  Coxe's  and  Heller 
&  Brightly's,  284. 

Chaldean  iron  wheel,  92. 

Chanzler's  (Eichard)  diagonal  scale,  or  method  of  transversals,  123,  209. 

China:  ancient  astronomical  observations,  92;  dry  compass  introduced  from  Japan, 
240 ;  earliest  wet  compass  in,  240 ;  mapping,  238. 

Chrismar's  improved  support  for  mounting  instruments,  27. 

Circumferentor  :  application  of  the  name,  287 ;  described  by  Bion,  219 ;  Jones's,  71. 

Clamp-and-tangent  invented  by  Hevelius,  16. 

Classification  of  surveying-instruments,  289. 

Clinometer,  classified  place,  289. 

Colvin,  Verplanck,  invention  of  disappearing  stadia-hairs,  42. 

Combes's  (C.) :  eccentric  theodolite,  28;  Morin's,  transit  (mine-theodolite),  classified 
place,  290;  side-telescope  mine-theodolite,  104,  170;  transit  (mine-theodolite), 
classified  place,  290. 

Compass ;  Agricola's,  classified  place,  289 ;  application  of  the  name,  287 ;  Weisbach's 
manner  of  suspending,  [24] ;  Chinese  invention,  240 ;  classified  place,  289 ;  dry, 
earliest  in  Europe,  240;  early  use,  94;  first  European,  240;  fleur-de-lis  upon, 
241;  Gioja's  supposed  invention,  241;  hanging,  221,  242;  hanging,  classified 
place,  290 ;  in  mine-surveys,  use  of,  first  described  in  German  treatise  in  1505, 
68 ;  lack  of  precision,  221 ;  magnetic,  classified  place,  290 ;  merit  of  the,  244 ; 
needle  dip,  241 ;  needle  with  vernier,  244;  on  telescope,  113,  145,  220 ;  plotting 
with,  241;  protractor  for  mine-surveys,  9,  10;  solar,  classified  place,  290;  solar, 
see  Solar  compass;  square  (boussole  carree),  application  of  the  name,  288;  Stan- 
ley's prismatic-compass  dial,  46 ;  supposed  gravitational  error,  222,  242  ;  -survey- 
ing, Fenwick's  complete  system,  96 ;  under  the  horizontal  divided  circle,  or  on 
top  of  the  telescope,  103;  unnecessary,  118;  unsatisfactory  for  high-class  mine- 
surveys,  64;  variation,  daily  change,  241;  variation,  mentioned  by  Adsiger,  241 ; 
wet,  early,  in  China,  240 ;  see  also  Mine-compass  and  Setz-compass. 

Compound  center  for  ordinary  use  made  feasible  by  Heller  and  Brightly,  277. 

Conical  graduation,  113;  compared  with  flat,  272. 

Cooke  &  Son's:  luminous  level  tube,  67 ;  theodolite,  209,  210;  transit,  116. 

COOPER,  JAS.  B. :  remarks  in  discussion  of  Mr.  Scott's  paper  on  the  evolution  of  mine- 
surveying  instruments,  121. 

Co-ordinate  method  of  plotting,  117;  suggested  by  B.  Williams  for  underground  sur- 
veys, 96. 

Cord,  classified  place  as  distance-measurer,  289. 

Cord-surveying :  at  Longdale,  Va.,  129  et  seq. ;  at  Low  Moor,  Va.,  124  et  seq. ;  von 
Miller-Hauenfels's  rule,  133  et  seq. 

Cortes,  Martin,  on  the  astrolabe,  166. 

Coxe's  (E.  B.) :  chain-tape,  32,  284;  plummet-lamp,  283,  303. 

Craft's  (G.  H.)  horseshoe-base  transit,  23,  77,  149. 

Cross-hairs:  first  used  by  Gascoigne,  260;  first  use  of  spiders'  webs,  70;  illuminated 
through  hole  in  axle,  100;  illumination  through  hole  in  axle,  devised  by  Usser, 
59;  invention  of,  206;  lighted  with  Heller's  adjustable  lamp-stand,  280  ;  lighting, 
307;  not  used  in  Gascoigne's  micrometer,  301 ;  of  platinum  for  surveying-instru- 
ments, introduced  by  Heller  &  Brightly,  260 ;  spider-webs  said  to  have  been 
proposed  by  Fontana,  20 ;  spider-webs  suggested  by  Eittenhouse,  20 ;  Troughton's 
alleged  first  use  of  spider-webs,  20. 

Cseti's  (O.)  leveling  telescope,  32. 

Cyclotomic  circles,  120. 

D'Abbadie's  use  of  the  objective-prism  on  a  theodolite,  52. 

DAVIS,  J.  B. :  History  of  Solar  Surveying  Instruments,  172 ;  solar  screen  for  surveying  in- 
struments, 65,  175;  solar  transit:  193  et  seq.;  description,  195  et  seq. ;  determin- 


312  INDEX. 

ing  latitude,  205;  determining  meridian,  204;  figures,  196,  197;  first  form,  194; 
history  of  origin,  193;  operation,  200  et  seq. ;  setting  telescope  for  latitude,  203. 

Davis  of  Derby,  modification  of  Hedley  dial,  46. 

Davis's  (Prof.  J.  B.)  encomiums  on  Heller  &  Brightly,  281. 

Declination  of  the  magnetic  needle :  10,  241 ;  variation  of  magnetic,  first  ascertained, 
241. 

Delhi  astronomical  instrument  of  marble,  93. 

Diagonal  scale  for  arcs,  or  method  of  transversals,  123,  209. 

Dial :  9 ;  Adams's,  15 ;  application  of  the  name,  287 ;  E.  T.  Newton  &  Son's,  18 ;  Hed- 
ley, Stanley's,  219 ;  Lean's,  the  first  telescopic  mine-instrument,  17 ;  old  English 
miner's,  14,  15 ;  Stanley's,  15 ;  -surveying,  Fenwick's  complete  system,  96. 

Digges,  Leonard,  invention  of  the  telescope,  252  et  seq. 

Digges's:  Pantometria,  5;  theodelitus,  6,  95;  theodelitus,  classified  place,  289;  theode- 
litus,  merely  an  astrolabe,  288  ;  topographicall  instrument,  262 ;  topographical 
instrument,  classified  place,  290 ;  topographical  instrument  essentially  a  theo- 
dolite, 288. 

Digges,  Thomas,  completer  of  L.  Digges's  book,  252. 

Dip  of  magnetic  needle,  241. 

Disappearing  stadia-hairs,  65,  142. 

Discussion  of  Mr.  D.  D.  Scott's  papef  on  the  evolution  of  mine-surveying  instru- 
ments, 68  et  seq. 

Distance-measurers  as  a  class,  289. 

Diurnal  change  of  compass  variation,  241. 

Dividing-engine,  Kamsden's,  228,  270. 

Divining-rod,  2. 

Dollond,  John  ;  invented  achromatic  telescope,  19 ;  patented  achromatic  lens,  261. 

Double  target  for  side-telescope,  280. 

Douglas's  "  Infallible  "  surveying-instrument :  69,  [167] ;  classified  place,  289. 

Draper,  Edmund:  26,  270,  298;  his  first  transit,  295;  mine-transit,  25;  shifting  tri- 
pod-head, 274 ;  top-auxiliary  telescope,  39. 

Eccentricity- correction  with  side-telescope,  31,  108. 

Eccentric:  instrument,  Borchers',  26,  27  ;  telescope  in  English  mine-surveying,  31. 

Egyptian:  ancient  astronomical  observations,  92;  map  of  a  gold-mine,  93 ;  supposed 

origin  of  surveying,  238. 
Eisenscheibe  :  application  of  the  name,  287 ;  classified  place,  289 ;  graduated  in  two 

ways,  87;  Moehling's,  302;  Studer's,  classified  place,  290;  von  Oppel's,  86;  von 

Voith's  Hoeschel's,  84. 
Electric:  currents  affecting  compass  at  Lake  Superior,  147;  lamps  (portable)  used  in 

mine-surveying,  126, 128,  215. 
Engineer's  theodolite,  Hoskold's,  230  et  seq. 
English  :  adherence  to  the  theodolite  wondered  at  by  Americans,  19 ;  tripod-heads  with 

four  leveling-screws  narrow,  274. 
Equatorial  adapter,  Berger's,  293,  295. 
Errata,  323. 

Everest's:  concentric-model  theodolite,  19,  116,  121;  tribrach  locking-plate,  30. 
Evolution  of  Mine-Surveying  Instruments  (ScOTT),  1;  concluding  discussion,  293. 
Evolution  of  the  theodolite,  225. 

Extensible  tripod,  137 ;  Heller  &  Brightly's,  277  ;  Hoskold's,  215. 
Eyre,  J.,  on  the  circumferentor  of  1654,  10. 

Fast-needle  dialing  originated  by  Fenwick,  47. 

Fauth  &  Company's  duplex-bearing  mine-transit,  56. 

Fenwick:  "fast-needle"  (circumferentor),  96;  originator  of  fast-needle  dialing,  47; 

system  of  mine-surveying,  24. 
Fineness  of  graduation,  63,  113, 120,  208,  271. 


INDEX.  313 

Flat-center :  disadvantages  of,  277 ;  transits  now  comparatively  rare,  277. 
Fleur-de-lis  on  compass,  241. 
Flint-glass  method  invented  by  Guinand,  261. 
Florian's  rule  for  the  Gradbogen,  135. 

Fluid  achromatic  object-glass  :  contrived  by  Blair,  261;  practically  useless,  262. 
Fontana,  Prof. :  claimed  invention  of  the  compound  microscope,  255 ;  said  to  have  pro- 
posed spider-webs  for  cross-hairs,  20. 
Fraunhofer's  improved  objectives  [19]. 
Freiberg  brackets,  26. 

French  method  of  mounting  eccentric  telescopes,  36. 
Fric  Brothers'  mine-theodolite,  53. 

Gale  (J.)  published  traverse-tables,  47. 

Galileo's  :  account  of  his  re-invention  of  the  telescope,  257 ;  first  telescope's  reception 
at  Venice,  258 ;  re-invention  of  the  telescope  [248],  257 ;  telescope,  7 ;  telescopes, 
size  of,  258. 

Gang-plank  (Spreitzen)  support  for  surveying-instruments,  38,  302,  305. 

Gardam's  (J.)  solar  transit,  188,  189. 

Gascoigne  (William) :  first  crossed  filaments  at  telescope  focus,  206;  first  used  cross- 
hairs, 260 ;  invented  micrometer,  43,  207,  259 ;  originated  stadia-measurement, 
207. 

Geiseler's  (E.  A.)  nadir-instrument,  23. 

Gensanne's  graphometre :  287 ;  classified  place,  289. 

Geodolite,  Stanley's,  306. 

Geometrical  square,  263. 

Geometry,  supposed  invention  in  Egypt,  238. 

German  (old)  method  of  establishing  unit  of  length  for  surveying,  71. 

Gioja  (F.),  supposed  inventor  of  compass,  241. 

Giuliani's  catageolabium,  16,  82,  86. 

Goniometer,  Junge's :  37 ;  classified  place,  290. 

Government  land-surveys,  general  method,  175. 

Gradbogen :  [242] ;  classified  place,  289 ;  Junge's  experiments,  135 ;  rules  of  von  Mil- 
ler-Hauenfels,  134. 

Grade-controlling  device  in  underground  working,  125. 

Gradienter-screw,  41. 

Gradiometer,  Stanley's,  41. 

Graduated  instruments  as  a  class,  289. 

Graduation :  centesimal,  29 ;  by  Young,?29 ;  conical,  or  beveled-edge,  113  ;  do.  compared 
with  flat,  272;  cylindrical,  209;  fineness,  63,  113,  120,208,271;  numbering  in  one 
direction  only,  64;  numbering  continuous  round  the  circle,  137. 

Grady's  (Peter)  duplex- bearing  mine-transit.  160. 

Graphometre:  prior  to  invention  of  vernier,  70;  application  of  the  name,  287;  de- 
scribed by  Bion,  227,';  Gensanne's,  classified  place,  289;  Komarzewski's,  classified 
place,  290  ;  souterrain  of  Komarzewski,  16. 

Green's  (William)  micrometer-lines  for  subtense  measurement,  42. 

Gregory,  James,  proposed  reflecting  telescopes,  261. 

Grouping  of  surveying  instruments,  288. 

Guinand  invented  flint-glass  method,  261. 

Gunter's  chain,  8,  284. 

Gurley's:  mine-transit,42 ;  quick -leveling  tripod-head,  57;  top-auxiliary  telescope,  39. 

Hall,  Chester  Moor,  first  made  achromatic  lens,  261. 

Hanging-compass :  8,  9,  221,  242 ;  adjustable,  9 ;  classified  place,  290 ;  first  illustra- 
tion, 9;  recent  use  in  Va.  and  Pa.,  25;  use  at  Longdale,  Va. :  129  et  seq. ;  use  at 
Low  Moor,  Va.,  124  et  seq. 

Hanging-lamp  of  Weisbach,  303. 


314  INDEX. 

Hanstadt's  (J.  N.  L.,  von) :  mine-theodolite,  169  et  seq. ;  system  of  mounting  instru- 
ments, 37. 

HARDEN,  JOHN  H. :  Notes  on  Tripod-Heads,  with  Reference  to  Mr.  Dunbar  D.  Scott's  Paper 
on  the  Evolution  of  Mine-Surveying  Instruments,  290  ;  improved  Hoffman  tripod- 
head,  45. 

Hassler's  (F.  E.)  instrument  with  perforated  vertical  axis,  20. 

Hedley's  (John)  dial,  31,  45;  Stanley's,  219. 

Heller,  Charles  S.,  281,  299  ;  shifting  tripod-head,  276. 

Heller  &  Brightly:  adjusting  screws  for  auxiliary  telescopes,  299;  apply  Kellner  lens 
to  erecting  telescope,  262;  auxiliary  side-telescope,  280;  auxiliary  top-telescope, 
280  ;  chain-tape,  284 ;  device  for  setting  a  transit  precisely  under  a  plumb-bob,  278 ; 
extensible  tripod-legs,  277 ;  firm  of,  281 ;  improvements  in  transits,  276;  introduced 
platinum  cross-wires,  260;  method  of  attaching  and  detaching  the  transit  on  the 
tripod,  277;  mining-transit,  description,  279 ;  mining-transit,  figure,  278,  279;  Prof. 
J.  B.  Davis's  encomiums  on,  281 ;  reflector  for  angle-reading,  280;  right-angle  sights, 
277 ;  spherical  metal  cups  and  balls  for  leveling-screws,  270  ;  sunflower,  281 ;  tan- 
gent-screw without  lost  motion,  277;  transit,  276;  tripod-head  leg-cheeks,  278; 
use  of  plumbago  as  lubricant,  278. 

Henderson's  ( J.)  rapid  traverser :  13,  69,  164  et  seq.,  [167] ;  its  classified  place,  289. 

Hero  of  Alexandria,  his  diopter  the  origin  of  the  theodolite,  1. 

Hevelius  :  improved  adjustment  of  Vernier's  scale,  16;  invented  clamp-and-tangent, 
16. 

Hildebrand's  solar  apparatus,  86. 

Hinged-standard  transit  of  Hulbert's  design,  148. 

Hipparchus  invented  astronomical  instruments,  93. 

History  of  Solar  Survey  ing -Instruments  (DAVIS),  172. 

Hoeschel's  Scheibeninstrument,  84. 

Hoffman's  (Daniel) :  quick-leveling  tripod-head,  45,  292. 

Hoffman-Harden  quick-leveling  tripod-head  [57],  76,  157,  276. 

Holmes's  solar  theodolite,  185. 

Homer's  mention  of  surveying,  239. 

Hooke  suggested  micrometer  hairs,  259. 

Horseshoe-base  transit :  Hulbert's  design,  148 ;  made  by  Buff  &  Berger  for  G.  H.  Crafts, 
23,  77,  149. 

HOSKOLD,  H.  D.:  remarks  in  discussion  of  Mr.  Scott's  paper  on  the  evolution  of 
mine-surveying  instruments,  91 ;  Remarks  on  Mine-Surveying  Instruments,  with  spe- 
cial Reference  to  Mr.  Dunbar  D.  Scott's  Paper  on  their  Evolution,  and  its  Discussion, 
206 ;  his  angleometer,  30,  31, 104  et  seq,,  236 ;  circular  protractor,  117 ;  engineer's 
theodolite,  98  et  seq,,  230  et  seq.;  engineer's  theodolite  criticised,  120;  extensible 
tripod,  215;  miner's  transit  theodolite,  44,  95  et  seq,  ;  nadir-instrument,  22 :  shift- 
ing tripod-head,  214, 276 ;  success  in  connecting  surface-lines  and  underground 
workings,  112 ;  surveying  compass,  107,  108 ;  verifying  telescope,  44. 

Houghton's  (Thomas) :  early  mention  of  compass  for  surveying,  94  ;  treatise  on  sub- 
terranean surveying,  8. 

HULBERT,  EDWIN  J. :  remarks  in  discussion  of  Mr.  Scott's  paper  on  the  evolution  of 
mine-surveying  instruments,  146;  horseshoe-base  transit  design,  148;  improved 
mine-transit,  162 ;  Lake  Superior  transit,  148 ;  original  side-telescope  transit, 
150, 151;  shifting  tripod-head,  150;  side-telescope  transit,  146,  148,  161;  success- 
ful surveys  with  his  Lake  Superior  transit,  150;  transit-instrument,  "  Lake  Su- 
perior pattern,"  160. 

HUNGERFORD,  W.  S. :  remarks  in  discussion  of  Mr.  Scott's  paper  on  the  evolution  of 
mine-surveying  instruments,  123. 

Huyghens:  discovered  an  object  to  be  visible  at  the  focus  of  Keplerian  telescope,  19 ; 
his  "telescope  without  tubes  "  first  described  in  1684,  206. 

Ibanez's  (General)  improvement  of  Hassler's  instrument,  20. 
Inclination-balance,  Tiberg's  [13],  69. 


INDEX.  315 

Infallible,  Douglas's:  classified  place,  289;  surveying  instrument,  69. 
Interchangeable:    auxiliary  telescope,  61,  64,  140 ;  solar  auxiliary's  diaphragm,  293, 

295. 

Inverting  telescope  in  surveying  :  advantages  over  erecting,  262  ;  desirable,  62,  124. 
Iron  disk  (Eisenscheibe) :  application  of  the  name,  287;  definition,  168. 
Iron  wheel,  Chaldean,  92. 

Jahr's  theodolite,  126. 

Jansen's  telescope,  7. 

Japan  :  dry  compass  introduced  from  Europe,  240 ;  old  style  mapping,  238 ;  trans- 
mitted dry  compass  to  China,  240. 

JOHNSON,  J.  E.,  JR.  :  remarks  in  discussion  of  Mr.  Scott's  paper  on  the  evolution  of 
mine-surveying  instruments,  129. 

Jones's  (W.  &  S.)  circumferentor,  16,  17,  71. 

Jordan  de  Rivalto,  Friar,  early  mention  of  spectacles,  246. 

Jordan's  (S.)  system  of  noting  angles,  29. 

Junge's  (A.):  experiments  with  the  Gradbogen,  135;  goniometer,  37;  classified  place 
of  goniometer,  290. 

Kastner,  Hofrath,  quadrant-clinometer,  9. 

Katageolabium,  Giuliani's,  16,  82,  86. 

Kawerau's  support  for  mounting  instruments,  28. 

KELLERSCHON,  JULIUS  :  remarks  in  discussion  of  Mr.  Scott's  paper  on  the  evolution 
of  mine-surveying  instruments,  133. 

Kellner  lens  in  erecting  telescope,  applied  by  Heller  &  Brightly,  262. 

Keplerian  telescope :  Huyghens  discovered  an. object  to  be  visible  at  the  common 
focus  of  the  lenses,  19;  used  for  astronomy,  261. 

Kepler:  his  account  of  Porta's  knowledge  of  the  telescope,  248  ;  suggested  inverting 
telescope,  256. 

Keuffel  &  Esser's :  aluminum  mine-transit,  30 ;  concentric  instrument  with  side- 
auxiliary,  35  ;  duplex-bearing  mine-transit,  56. 

Koebel,  J. :  credits  Egyptian  invention  of  surveying,  238;  his  early  work  on  survey- 
ing, 71. 

Komarzewski's  graphometre:  souterrain  [16],  84 ;  an  improved  Eisenscheibe,  287; 
classified  place,  290. 

Lake  Superior :  early  mine-surveying  conditions,  146 ;  pattern  of  transit  with  eccen- 
tric telescope,  36,  148  ;  successful  surveys,  150. 

Lament's  magnetic  theodolite,  13. 

Lamp:  on  bracket  to  light  cross-hairs,  307;  -stand,  Heller  &  Brightly's  adjustable, 
for  lighting  cross-wires,  280 ;  Weisbach's  hanging,  303;  Weisbach's  Setzlampe,  305. 

Larsson's  (Per)  top-auxiliary  telescope,  40. 

Lean's  dial:  15;  the  first  telescopic  mine-instrument,  17. 

Level,  classified  place,  289. 

Leveling-screws :  four,  137;  method  of  four  described,  and  its  advantages,  272; 
method  of  three  described,  and  its  defects,  272;  on  leather  washer,  270;  on  metal 
cups,  270;  on  spherical  metal  cups  and  balls,  270  ;  three,  103,  306  ;  three  or  four, 
76,  211,  272. 

Leveling-telescope,  Cseti's,  32. 

Levels,  luminous,  145. 

Lippershey,  Hans :  his  accidental  discovery  of  telescope  principle,  256 ;  invented  re- 
fracting telescope,  255. 

Locke's  hand-level,  155. 

"  Locke's  sights  "  substituted  for  telescope,  155. 

Longdale,  Va.,  iron-mines:  general  arrangement,  130;  surveys,  130. 

Lop-sided  target  for  side-telescope  [242],  280. 


316  INDEX. 

Low  instruments,  advantage  of,  in  shallow  mine-workings,  76. 

Low  Moor,  Va.,  iron-mines :  general  arrangement,  123 ;  surveys,  123. 

Luminous  levels,  145. 

Lunette  murale,  172. 

LYMAN,  BENJ.  SMITH  ;  Notes  on  Mine-Surveying  Instruments,  with  Special  Reference  to 

Mr.  Dunbar  D.  Scott's  Paper  on  their  Evolution,  and  its  Discussion,  237  ;    his  solar 

transit,  180 ;  his  use  of  glass  stadia-rods,  42. 

Magnetic:  bearings  unnecessary,  118;  declination  at  Lake  Superior,  147;  needle, 
claimed  to  have  been  first  mounted  by  Flavio  Gioja,  of  Amain,  4;  needle,  de- 
clination or  variation,  10 ;  needle,  of  the  Chinese  Emperor  Hwang-ti,  4 ;  needle 
unfit  for  high-class  mine-surveys,  64 ;  observations  connecting  surface- and  un- 
derground-surveys, 33;  survey  accuracy,  Ernst- August  adit-level,  Harz,  55. 

Magnetometer,  Thalen's,  69. 

Malvasia,  Marquis,  use  of  silk  fibers  for  cross-hairs,  19. 

Maurice,  Prince  of  Orange,  Count  of  Nassau,  possessed  first  telescope,  257,  256. 

Mayer,  J.  E.,  introduced  stadia-hairs  in  America,  300. 

Mayer,  Tobias,  introduced  method  of  repetition  of  observed  arcs,  50. 

McNair's  (Thos.  S.)  inclined -standard  mine-transit,  48,  158,  159. 

Meridian-determination,  old  methods,  174. 

Meridian,  true,  best  for  reference  of  survey-lines,  64. 

Metius,  James  (properly  called  Jacob  Adriauzoon),  later  invented  refracting  telescope, 
255. 

Microscope,  compound :  invention  claimed  by  Fontana,  255 ;  invention  claimed  for 
Jansen,  255 ;  probably  invented  by  Drebel,  255. 

Micrometer:  devised  by  Gascoigne,  43;  early  continental,  had  silver  wires  and  silk 
fibers,  259 ;  -hairs  suggested  by  Hooke,  259 ;  invented  by  Gascoigne,  259 ;  -micro- 
scope on  Hoskold's  theodolite,  115 ;  -microscope,  Troughton's,  58. 

Mifllin,  S.  W.,  decimal  graduation  of  surveying  instruments  introduced  by,  29. 

Miller-Hauenfels,  A.  von,  rules  for  the  Gradbogen,  9,  134. 

Mine-compass:  Agri cola's,  217 ;  of  1518,  216;  of  1541,  217. 

Mine-plans,  early,  9. 

Miner's  dial,  old  English,  14,  15. 

Mine-surveying:  Butler  Williams's suggestion  (1842)  of  use  of  theodolite,  96 ;  (ear- 
liest) in  England,  93;  Fenwick's  system,  24;  first  accurate  underground,  17; 
forgotten  for  several  centuries,  93 ;  general  system  solely  with  theodolite  first 
published  in  England,  1863,  by  H.  D.  Hoskold,  96 ;  German  book  of  1504,  216 ; 
graphic  method  used  in  Sweden  at  beginning  of  eighteenth  century,  12 ;  mag- 
netic, 14 ;  in  1778,  according  to  W.  Pryce,  14 ;  progress  in  nineteenth  century, 
31;  relative  progress  in  America,  Germany  and  England.  31;  T.  Houghton's 
methods,  8,14;  with  Lean's  dial,  17;  with  side-telescope,  in  England,  31;  with 
theodolite,  attempt  to  introduce  by  Combes  and  D'Aubuisson,  96. 

Mine-surveying  instruments :  ancient  history,  4,  238  ;  evolution  of,  1  et  seq.  ;  Lean's 
dial,  17 ;  Notes  on,  by  B.  S.  LYMAN,  237  et  seq. ;  Remarks  on,  by  H.  D.  HOSKOLD, 
216  et  seq. 

Mine-theodolite :  Breithaupt's  modern,  38 ;  Combes's,  classified  place,  290 ;  precision, 
236. 

Mine-transit:  Brandis,  299;  Breithaupt's,  18;  Draper's,  25 ;  first  distinctive  Ameri- 
can, 25;  Gurley's,  42;  Heller  &  Brightly's,  description,  279;  figures,  278,  279 ; 
Keuffel  &  Esser's  aluminum,  30  ;  McNair's,  48;  -theodolite  first  published  in  1863 
by  H.  D.  Hoskold,  96. 

Minot,  and  tacheometry  in  France  [29]. 

Moehling's  Eisenscheibe,  302. 

Montanari  (G.)  invented  stadiametric  principles,  301. 

Morin's  Combes's  transit  (mine-theodolite),  28 ;  classified  place,  290. 


INDEX.  317 

Mullouey's  (J.  F.)  mining-dial,  155. 

Mural  circle :  devised  by  Maskelyne,  172 :  telescope,  analogy  to,  in  some  surveying 

instruments,  288. 
Mural  quadrant,  described  by  Ptolemy,  constructed  by  Nasir-eddin,  172. 

Nadir  dial,  Troughton  &  Simms'  prismatic,  22. 

Nadir-instrument:  by  Buff  &  Berger,  23 ;  designed  by  C.  L.  Berger  for  G.  H.  Crafts, 

23,  77 ;  F.  E.  Brandis'  Sons',  23 ;  E.  A.  Geisler's,  23 ;  Hoskold's  22 ;  Nagel's,  21. 
Nadir  mining-theodolite,  Stanley's,  306. 
Nagel's  (Prof.  A.)  nadir- instrument,  21. 
Names  of  surveying  instruments,  286. 
Near-sighting,  65. 

Newton,  I.,  made  reflecting  telescope,  261. 
Newton  &  Son's  (E.  T.),  dial,  18;  telescope-mount,  18. 
Nonius:    invented,  209;  -plate  on  surveying-compass,  155;    vernier,  erroneously  so 

called,  59. 
Notes  on  Mine- Survey  ing  Instruments,  with  Special  Reference  to  Mr.  Dunbar  D.  Scott's  Paper 

on  their  Evolution,  and  its  Discussion  (LYMAN),  237. 
Notes  on  Tripod-Heads,  with  Reference  to  Mr.  Dunbar  D.  Scott's  Paper  on  the  Evolution  of 

Mine-Surveying  Instruments  (HARDEN),  290. 
Nunez,  Pedro,  system  of  quadrant-readings,  60. 

Objective  prism  :  in  telescope  51;  in  d'Abbadie's  theodolite,  52. 
Objective-reflector,  307. 
Octant :  224,  226 ;  classified  place,  289. 

Ohio  Society  of  Surveyors  and  Civil  Engineers'  Committee  on  Solar  Transits,  193. 
Omnimeter,  Bell-Elliott-Eckhold's,  191. 
Orientation-instrument  with  side  telescope,  Tesdorpf 's,  55. 

OWEN,  FRANK  :  remarks  in  discussion  of  Mr.  Scott's  paper  on  the  evolution  of  mine- 
surveying  instruments,  164. 

Pearson's  (H.  C.)  solar  transit,  182. 

Petherick's  (Wm.)  mine-transit  with  first  of  top-auxiliary  telescopes,  157. 

Picard,  Jean,  use  of  silk  fibers  for  cross-hairs,  19. 

Plane-table :  attributed  to  Praetorius,  12;  Beighton's,  with  telescopic  alidade,  described 

by  F.  W.  Simms,  74;  classified  place,  289;  described  in  Stone's  Bion,  223;  (first) 

the  Praetorian  mensula,  72 ;  may  have  originated  in  the  three-legged  stool,  94  : 

Searle's,  71. 

Planisphere  or  circle  called  Theodelitus,  263. 
Platinum  cross- wires:  first  used  in  telescopes  by  Wollaston,  302;  introduced  by  Heller 

&  Brightly,  260. 

Plotting,  co-ordinate  method,  117. 
Plotting  with  compass,  241. 

Plumbago  used  as  lubricant  by  Heller  &  Brightly,  278. 
Plumb-line  deflection,  222. 

Plumb-lines  in  shafts,  Hoskold's  comments,  215;  Hulbert's  experience,  149. 
Plummet-lamp,  Coxe's,  283,  303. 
Pole,  classified  place  as  distance  measurer,  289. 
Porro's  (M.)  topographometric  instrument  "  Cleps,"  43. 

Porta,  Giambattista  della,  his  supposed  invention  of  the  telescope,  248  et  seq. 
Praediger's  mine-theodolite,  78. 
Praetorian  mensula,  72. 

Praetorius,  Johann,  invented  the  plane-table,  72. 
Precision  of:  mine-theodolites,  236;  the  compass,  221,  244. 
Preece's  (W.)  telescopic  Hedley  dial,  451. 
Prince,  Isaac,  on  declination  of  the  magnetic  needle,  11. 


318  INDEX. 

Proclus,  early  history  of  geometry,  238. 

Protractor  arranged  for  correcting  side-telescope  eccentricity,  108. 

Ptolemy's  (Claudius) ;  astronomical  instruments,  93  ;  mythical  spyglass,  251. 

Quadrant:  classified  place,  289;  early  use,  94,  95;  early  dates,  224;  geometrical!,  Dig- 

ges's,  262,  263. 
Queen  &  Company's  hanging-compass,  25. 

Eamsden's  (Jesse) :  alleged  transit-principle,  19,25,  267,  295;  circular,  dividing-en- 
gine, 16,  96,  228,  270, 295 ;  36-in.  theodolite,  228. 

Eapid  traverser,  Henderson's :  [69] ;  classified  place,  289. 

RAYMOND,  E.  W. :  remarks  in  discussion  of  Mr.  Scott's  paper  on  the  evolution  of 
mine-surveying  instruments,  166;  on  the  divining-rod,  3;  on  the  surveyor's 
chain,  32. 

Eees's  illustration  of  Troughton's  portable  transit,  297. 

Eeflecting  telescope :  made  by  Newton,  261 ;  proposed  by  Gregory,  261. 

Eeflector :  at  objective,  307;  to  aid  angle-reading,  Heller  &  Brightly's,  280. 

Remarks  on  Mine-Surveying  Instruments,  with  Special  Reference  to  Mr.  Dunbar  D.  Scott's 
Paper  on  their  Evolution,  and  its  Discussion  (HOSKOLD),  206. 

Eeichenbach's  "broken  telescope,"  54/ 

Eepetition  of  observed  arcs,  a  method  introduced  by  Mayer  and  Borda,  50. 

Eibero's  (Diego),  1529,  figures,  quadrants  and  astrolabes,  95. 

Eight-angle  sights,  Heller  &  Brightly's,  277. 

Eittenhouse,  David:  chain,  32,  283;  early  made  surveying-instruments,  152;  "first 
American  telescope,"  20,  260;  first  used  vernier  for  variation-allowance,  155;  in- 
vented spider-web  cross-hairs,  259 ;  suggested  spider-webs  for  cross-hairs,  20. 

Eodgers,  of  London,  improved  objectives  [19]. 

Eoemer's  invention  of  astronomical  transit  instrument,  172,  296. 

Eossler,  Balthazar,  compass  and  clinometer,  7. 

Saegmuller's  (G.  N.) :  detachable  objective-prism,  51;  double-reflecting  objective- 
prism,  52  ;  solar  transit,  189 ;  telescopic  solar,  44,  50,  52,  60. 

Scheibe,  Zollmann's,  classified  place,  289. 

Scheiner,  constructed  inverting  telescope,  256. 

Schmidt's  centering  apparatus  for  shaft  plumb-lines,  33,  34  [58];  criticised,  149; 
Freiberg  brackets  for  mounting  instruments,  27. 

SCHMIDT,  PROF.  DK.  MAX  :  remarks  in  discussion  of  Mr.  Scott's  paper  on  the  evolu- 
tion of  mine-surveying  instruments,  82. 

Schmoltz's  (William)  solar  attachment  for  transits,  43;  solar-transit,  178. 

Schneider  clinometer,  9. 

SCOTT,  DUNBAR  D. :  The  Evolution  of  Mine-Surveying  Instruments,  1 ;  remarks  in  dis- 
cussion of  his  paper  on  the  evolution  of  mine-surveying  instruments,  71,  76,  86, 
119,  126,  293;  his  mine-tachymeter,  61  et  seq.,  137,  307  ;  his  tachymeter  criticised, 
109,140  et  seq.,  285;  his  tachymeter  defended,  121 ;  his  tachymeter,  Hosk old's 
comments,  228. 

Scott's  (Walter)  solar  attachment,  192. 

Searle's  plane-table,  71. 

Searle's  (B.)  side-telescope  transit,  300. 

Secretary's  note  on  the  discussion  of  Mr.  D.  D.  Scott's  paper,  68. 

Seibert's  (F.  E.)  solar  transit,  181,  182;   transit  with  inclined  standards,  47. 

Setz-compass,  5 ;  classified  place,  289 ;  of  1541,  4  ;  Voigtel's,  218. 

Setz-lampe,  Weisbach's,  305,  306. 

Sextant,  classified  place,  289, 

Shaft  plumb-lines:  Hoskold's  opinion,  216;  Hulbert's  experience,  149;  Schmidt's 
centering  apparatus,  33,  34,  [58]. 

Shaft-sighting,  96,  231. 


INDEX.  319 

Shaft-transit,  G.  H.  Craft's,  by  Buff  &  Berger,  23.  77,  149. 

Shifting  tripod-head  ;  Draper's,  274 ;  invented  by  Hulbert,  150 ;  Heller's,  276 ;  Hos- 

kold's,  214,  276;  Troughton  &  Simms's,  103,  212,274;    Win.  J.  Young's  [36],  153, 

270  [274],  291. 

Short's  telemeter-level  [41]. 
Side-auxiliary  telescope  on  vertical  circle,  35. 
Side-telescope:   attached  without  adjustment,  41;    auxiliary,  Heller  &  Brightly's, 

280;  correction  for  eccentricity,  31,108,280;  in  English  mine  surveying,  31; 

theodolites,  104 ;  -transit,  as  a  name,  288 ;  transit,  Hulbert's  original,  150,  151. 
Sighting  at  near  objects  with  telescope,  65. 

Sights :  right-angle,  Heller  &  Brightly's,  277 ;  telescopic,  first  used  by  Gascoigne,  260. 
Sight-vanes  in  mine-surveying  instruments,  origin  of,  38. 

Simms,  F.  W.,  description  of  Beigh ton's  plane-table  with  telescopic  alidade,  74;  illus- 
tration of  a  portable  alt-azimuth,  297. 
Sisson's  (Jonathan)  theodolite,  19. 
Sitius's  (F.)  citation  from  Porta  against  Galileo,  251. 
Smith-Hedley  dial,  156. 
Smith's  solar  transit,  186. 
Solar  adapter,  Berger's,  293,  295. 
Solar  apparatus,  Hildeb rand's,  86. 
Solar  attachment :  Buff&  Berger's,  184;  Buff  &  Berger's,  Pearson's,  183;  Pearson's, 

182 ;  Walter  Scott's,  192. 

Solar-compass :  Burt's,  43 ;  classified  place,  290. 

Solar  surveying  :  importance  of,  173;  -instruments,  history  of,  (DAVIS),  172  et  seq. 
Solar  theodolite,  Holmes's,  185. 
Solar  transit :  Berger's,  converted  from  Scott's  interchangeable  auxiliary  telescope, 

293;  Brandis's,  192 ;  Buff  &  Berger's  top-telescope  with  adjustable  trivet,  60; 

Davis's,  193;  errors  and  difficulties,  194;  Gardam's,  188;  limited  hours  for  good 

work,  199;    Lyman's,    180;    Saegmuller's,  189;    Schmoltz's,  43;    Seibert's  181; 

Smith's,  186. 
Spectacles  invented,  246. 
Spider-webs  for  cross-hairs :  alleged  first  use  by  Troughton,  20 ;  not  first  used  by 

Troughton,  260:  said  to  have  been  proposed  by  Fontana,  20,  260;  invented  by 

Eittenhouse,  259;  suggested  by  Eittenhouse,  20. 
Spirit-level,  straight  and  round  forms  compared,  270. 
Spreitzen  (gang-plank)  support  for  surveying  instruments,  38,  302,  305. 
Square  geometricall,  263. 
Stadia-hairs :    disappearing,  65,  142 ;    introduced  in  America  by  J.  E.  Mayer,  300 ; 

supposed  by  Prof.  Baker  not  to  have  been  used  in  America  until  after  the  Civil 

War,  43. 

Stadia-measurement  originated  with  Gascoigne,  207. 
Stadiametric  principle  invented  in  1674  by  G.  Montanari,  301. 
Stampfer's  Distanzmesser,  41. 
STANLEY,  W.  F. :  remarks  in  discussion  of  Mr.  Scott's  paper  on  the  evolution  of 

mine-surveying  instruments,  75  ;  geodolite,  306;  gradiometer,  41 ;  Hedley  dial, 

219  ;  improved  Hedley  dial,  75 ;  miner's  dial,  15  ;  nadir  mining  theodolite,  306 ; 

prismatic-compass  dial,  46. 
Steel-tape,  classified  place,  289. 
Steinheil's  use  of  the  objective  prism,  52. 

Striding-compass :  first  applied  to  mine-instruments,  55;  introduced  in  America,  55. 
String-surveying:  at  Lougdale,  Va.,  129  et  seq.;  at  Low  Moor,  Va.,  124  et  seq.;  von 

Miller-Hauenfels's  rule,  133  et  seq. 

Studer's,  J.  G.,  improved  Eisenscheibe :  11 ;  classified  place,  290. 
Subtense  measurement,  100,  115,  116 ;  micrometer  slides,  58. 
Sunflower :  classified  place,  289 ;  Heller  &  Brightly's,  281. 
Surface-lines  connected  with  underground  workings,  110,  112. 


320  INDEX. 

Survey,  accuracy  of  magnetic,  Ernst- August  adit-level,  Harz,  55. 

Surveying:  Assyrian,  92  ;  first,  239;  supposed  invention  in  Egypt,  238. 

Surveyor's  chain  :  R.  W.  Raymond's  criticism,  32;  Rittenhouse's,  32 ;  supplanted  by 
steel  tapes,  32. 

Surveys,  surface-  and  underground-  connected :  astronomical  method,  33 ;  Baker's 
method,  33;  Beanland's  method,  33;  Borchers's  method  [34]  ;  Bourns's  method, 
[34] ;  by  magnetic  observations,  33. 

Surveys,  topographical,  Prof.  Van  Ornum's  lecture  on,  72. 

Surveying-instruments:  Albrecht's  of  1673,  235:  American  first  transit,  25, 66, 67;  angle- 
orneter,  236;  Assyrian,  238;  Assyrian  astrolabe,  92 ;  astrolabe,  166 ;  astrolabium  and 
cross-staff  described  by  Mayer,  122;  Bartelot's  mining  compass,  154;  Beighton's 
plane-table  with  telescopic  alidade,  74;  Bell-Elliott-Eckhold  omnimeter,  191; 
Berger's  nadir-instrument  designed  for  G.  H.  Crafts,  77;  Brandis  solar  transit; 
191 ;  Brunton's  pocket-transit,  89  et  seq.  ;  Buff  &  Berger's  solar  attachment,  184  ; 
Buff  &  Berger's  Pearson's  solar  attachment,  183 ;  Burt's  solar  compass,  43,  175 ; 
Casella's  portable  theodolite,  30;  Cater's  prismatic  compass  dial,  46;  Combes's 
mine-theodolite,  170;  Cooke& Sons'  transit,  116;  Davis's  solar  screen,  65, 175;  Davis 
solar  transit,  193  et  seq.;  diaphragm  and  cross-hairs  first  used,  70;  Digges's  theode- 
litus,  95;  Digges's  topographical  instrument,  262  et  seq. ;  Douglas's  "  Infallible,"  69 
[167] ;  early  history,  91 ;  Egyptian,  238;  Fenwick's  "fast-needle"  (circumferen- 
tor),  96 ;  Gardam's  solar  transit,  188,  189  ;  Giuliani's  catageolabium,  82  ;  Grady's 
duplex-bearing  mine-transit,  160;  graphometre  described  by  Bion,  227  ;  grouped 
and  classified,  288 ;  hanging-compass,  242  ;  Heller  &  Brightly's  improvements,  276 
et  seq. ;  Heller  &  Brightly's  mine-transit,  278,  279 ;  Heller  &  Brightly's  sunflower, 
281:  Heller  &  Brightly's  transit,  276;  Henderson's  Rapid  Traverser  [69],  164  et 
seq.,  [167]  [289];  history  of  solar  (DA  vis),  172  etseq.;  Holrnes's  solar  theodolite,  185; 
Hoskold's  angleometer,  104  et  seq.;  Hoskold's  engineer's  theodolite,  230  etseq.; 
Hosk old's  surveying  compass,  107,  108 ;  Hulbert's  improved  mine-transit,  162 ; 
Hulbert's  side-telescope  transit,  148,  161;  Hulbert's  transit,  146  et  seq.;  Hulbert's 
transit  "  Lake  Superior"  pattern,  160;  iron-disk  (Eisenscheibe},  168;  Lean's  dial, 
17;  Locke's  hand-level,  155;  Lyman's  solar  transit,  180;  McNair's  inclined- 
standard  mine-transit,  158,  159;  Mulloney's  mining-dial,  155;  names,  286;  neces- 
sity of  surveyor's  adjustment  of,  34 ;  nomenclature  and  classification,  286  et  seq.  ; 
octant,  224,  226 ;  old  English  miner's  dial,  14,  15 ;  Pearson's  solar  transit,  182 ; 
Petherick's  mine-transit  with  first  of  top-auxiliary  telescopes,  157 ;  plane  table, 
in  Stone's  Bion,  223 ;  quadrant,  224 ;  Saegmuller's  solar  transit,  189  ;  Schmoltz's 
solar  transit,  178;  Scott's  mine-tachy meter,  61  et  seq.,  228 ;  Scott's  mine-tachy- 
meter  criticised,  285 ;  Searle's  side-telescope  transit,  300 :  Seibert's  solar  .transit, 
181,  182;  Smith-Hedley  dial,  156;  Smith's  solar  transit,  186;  square  geometricall, 
263 ;  tabulated  in  classes,  289 ;  transit,  267  et  seq. ;  Trough  ton's  portable  transit,  110 ; 
Voigtel's  mining-astrolabe,  119;  von  Hanstadt's  method  of  mounting,  37, 169,  302, 
304;  von  Hanstadt's  mine-theodolite,  169;  von  Oppel's  Eisenscheibe,  86;  Walter 
Scott's  solar  attachment,  192;  Yeiser's  meridian-instrument,  177;  Young's  "  Amer- 
ican engineer's  transit,"  153;  Young's  compound  "long-center"  transit,  153; 
Young's  gradienter,  159;  Young  &  Son's  modern  mine-transit,  161 ;  Zollman's 
disk,  167,  168. 

Tachymeter,  Scott's,  61  et  seq.,  307;  criticised,  109,  140  et  seq.,  285;  defended,  121. 

Tangent,  clamp  and,  invented  by  Hevelius,  16. 

Tangent-screw  without  lost  motion,  Heller  &  Brightly's,  277. 

Tanner's  subtense  method  of  determining  distances,  116. 

Tape:  classified  place,  289;  long  steel,  called  chain-tape,  284. 

Target,  double:  108;  or  lopsided,  for  side-telescope,  280. 

Targets,  interchangeable,  38. 

Target,  lopsided  [242]. 

Telescope:  accuracy  of  sighting  down  a  shaft,  149;  aerial,  261;  Draper's  top-auxiliary, 


INDEX.  321 

39 ;  disappearing  stadia-hairs,  42  ;  early  improvements  in,  19  ;  (eccentric),  French 
method  of  mounting,  36 ;  Galileo's,  7,  257  et  seq. ;  Gascoigne's  micrometer,  43 ; 
Green's  subtense  measurement,  42;  Gurley's  top-auxiliary,  39;  improvements, 
259;  invention,  7,  2££etseq. ;  inverting,  62, 124;  inverting,  advantage  over  erect- 
ing, 262;  inverting,  constructed  by  Scheiner,  256;  inverting,  suggested  by  Kepler, 
256;  interchangeable  auxiliary,  140;  Keplerian,  capable  of  having  an  object  visi- 
ble at  focus,  19 ;  Keplerian,  invented,  19 ;  Keplerian,  used  for  astronomy,  261 ; 
Larsson's  top-auxiliary,  40 ;  origin,  244;  reflecting,  invented  by  Digges,  254;  re- 
flecting, made  by  Newton,  261 ;  reflecting,  proposed  by  Gregory,  261 ;  refracting, 
invented  by  Lippershey,  255 ;  refracting,  later  invented  by  Adrianzoon,  255 ;  re- 
fracting, reinvented  by  Galileo,  257 ;  refracting,  supposed  invention  by  Jansen, 
255;  Eeichenbach's  broken,  54  ;  said  to  have  been  improved  by  Jansen,  7;  side- 
auxiliary,  34  et  seq. ;  sighting  near  objects,  65 ;  stadia  hairs,  43;  supposed  to  have 
been  known  in  Ovid's  time,  7 ;  supposed  to  have  been  known  to  Friar  Bacon,  7 ; 
top-auxiliary,  39;  verifying,  first  used  in  mine-transits  by  Hoskold,  44. 

Telescopic  sights  first  used  by  Gascoigne,  260. 

Tesdorpf's  (Ludwig)  orientation-instrument  with  side-telescope,  55,  57. 

Thalen,  Eobert,  magnetometer,  13  [69]. 

Theodolite  :  262  et  seq.  ;  Adams's  miniature,  296 ;  application  of  the  name,  287,  288  ; 
Breithaupt's  American  pattern,  59;  Breithaupt's  eccentric  mine-theodolite,  80; 
Breithaupt's  orientation-instrument,  54,  55;  Breithaupt's  pocket-,  30;  Casella's 
portable,  30;  Combes's  eccentric  mine-,  28,  30,  170;  Cooke's  luminous  level  tube, 
67;  Cooke's,  with  cylindrical  graduation,  209,  210;  d'Abbadie's,  with  objective- 
prism,  52;  Davis's  modification  of  Hedley  dial,  46;  derivation  of  the  word,  6, 
266;  Digges's  topographicall  instrument,  262  et  seq,  ;  double-reflecting  objective- 
prism,  53;  English  adherence  to,  wondered  at  by  Americans,  19;  Everest's  con- 
centric model,  19,  121;  evolution,  225;  Fric's,  53;  hinged  standards,  48,  49;  Hoff- 
man quickleveling  tripod-head,  45;  Holmes's  solar,  185;  Hoskold's  engineer's, 
98  et  seq.,  230  et  seq. ;  Hoskold's  miner's  transit-,  44,  95  et  seq. ;  inclined  standards, 
47 ;  Jahr's,  126 ;  Keuffel  &  Esser's  duplex-bearing  mine-transit,  56 ;  Komar- 
zewski's,  84;  miniature  forms,  Breithaupt's,  Casella's,  Keuffel  &  Esser's,  30; 
Morin's  method  of  mounting  telescope-,  28 ;  Nunez's  system  of  quadrant-read- 
ings, 59;  of  last  century,  now  called  Lean's  dial,  17;  old  cradle-type,  112;  origin, 
262  ;  origin  in  the  diopter  of  Hero  of  Alexandria,  1 ;  Praediger's  mine-theodolite, 
78;  Preece's  telescopic  Hedley  dial,  45;  Saegmuller's  telescopic  solar,  50,52,60; 
seven-inch  English  of  last  century,  18;  standard  model  English,  18:  Tesdorpf's 
eccentric,  57 ;  Viertel's  first  use  of,  in  vertical  shaft  surveys,  21 ;  von  Hanstadt's 
mine-theodolite,  169 ;  von  Voith's,  84  ;  Wagoner's  improvements.  50. 

Theodelitus,  Digges's  (1571) :  6,  95,  262  et  seq.;  classified  place,  289;  merely  an  astro- 
labe, 288. 

Three-legged  stool:  for  tripod,  14;  in  surveying,  classified  place,  289;  with  chalked 
string,  for  plane-table,  93. 

Three  leveliug-screws,  103,  272. 

Three-tripod  system  underground  suggested  by  B.  Williams,  96. 

Tiberg's  :  inclination-balance,  69 ;  magnetometer,  13. 

Toledo,  1067,  astrolabe,  95. 

Topographical  instrument,  Digges's:  essentially  a  theodolite,  288 ;  classified  place, 
290. 

Top-telescope :  auxiliary,  Heller  &  Brightly's,  280 ;  correction  for  observations,  280  ; 
Giuliani's  not  an  auxiliary,  86. 

Transit:  267  et  seq.;  application  of  the  name,  287,  288;  astronomical:  Steinheil's 
use  of  the  objective-prism,  52;  Batterman's,  50;  Breithaupt's  mine-,  18;  Buff  & 
Berger's  detachable  ball-and-socket  quick-leveling  tripod-heads,  57;  Buff  &  Ber- 
ger's  duplex-bearing  mine-transit,  56 ;  classified  place,  290 ;  compound  center  for 
ordinary  use  made  feasible  by  Heller  &  Brightly,  277;  Cooke  &  Sous',  116;  cyclo- 


322  INDEX. 

tomic  principle,  50  ;  definition  of,  172;  Draper's  early,  268;  Fauth  &  Company's 
duplex-bearing  mine-transit,  56;  first  application  of  the  striding-compass,  55; 
first  made  of  cast  bronze  in  1871  by  Heller  &  Brightly,  276 :  first  surveying-, 
263 ;  gradienter-screw  applied  to,  41,  159 ;  Heller  &  Brightly's  method  of  attach- 
ing and  detaching  on  the  tripod,  277;  hinged  standards,  designed  by  Hulbert,  148  ; 
horseshoe-base  designed  by  Hulbert,  148 ;  Hulbert's  Lake  Superior,  148;  Hul- 
bert's original  side-telescope,  150,  151 ;  -instrument,  portable,  used  by  Bourns  at 
the  Box  Tunnel,  109;  invented  by  W.  J.  Young,  25;  invention  claimed  for 
Young,  268 ;  invention  possibly  by  Draper,  268 ;  Lake  Superior  pattern,  36 ; 
mining-,  Heller  &  Brightly's,  description  and  figure,  278,  279 ;  portable,  Trough- 
ton's,  297;  -principle  of  Eamsden,  19,  25,  267;  Saegmuller's  detachable  objective- 
prism,  51  ;  Scott's  mine  tachymeter,  61  et  seq. ;  Searle's  side-telescope,  300 ;  -set- 
ting precisely  under  a  plumb-bob,  Heller  &  Brightly's  device  in  aid  of,  278; 
striding-compass  introduced  in  America,  55 ;  -telescope,  astronomical,  invented 
by  Eoemer,  172,  296 ;  -theodolite,  as  a  name,  288 ;  Young's  railway-,  298. 

Transversals,  method  of,  or  diagonal  scale,  123,  209. 

Traverser,  Henderson's  Kapid:  13,  [69],  164  et  seq.,  167;  classified  place,  289. 

Traverse-tables  published  by  J.  Gale,  47. 

Tripod,  extension,  137. 

Tripod-head  :  English,  with  four  leveling-screws  narrow,  274;  Gurley's  quick-level- 
ing, 57 ;  Hoffman's,  292 :  Hoffman's  improved  by  J.  H.  Harden,  45;  Hoffman- 
Harden,  76,  276 ;  shifting,  274  et  seq. ;  shifting,  Draper's,  274 ;  shifting,  Heller's, 
276;  shifting,  Hoskold's,  214,  276;  shifting,  invented  by  Hulbert,  150;  shifting, 
Trough  ton  &  Simms's,  103,  212,  274;  shifting,  Young's  patent,  153,  274,  291. 

Tripod-heads,  Notes  on,  by  J.  H.  HARDEN,  290  et  seq. 

Tripod-leg  cheeks,  Heller  &  Brightly's,  278. 

Tripod-legs:  291;  angular,  291;  extensible,  Heller  &  Brightly's,  277;  lattice-built, 
adjustable,  291;  round,  equal  diameter,  metallic  screw-joints  in  the  middle,  291; 
round,  larger  in  the  middle,  291. 

Troughton's;  alleged  first  use  of  spider-webs  for  cross-hairs,  20;  alt-azimuth,  297; 
micrometer-microscope,  58 ;  portable  transit-instrument,  110,  297. 

Troughton  &  Simms's  prismatic  nadir-dial,  22 ;  shifting  tripod-head,  103,  212,  274. 

Tunnel  section-measuring  with  the  sunflower,  282,  284. 

Underground  workings  connected  with  surface  lines,  110,  112. 

Ungraduated  instruments  as  a  class,  289. 

Usser  first  practiced  cross-hair  illumination  through  axle,  59. 

Valencia,  1086,  astrolabe,  95. 

Van  Ornum,  Prof.,  lecture  on  topographical  surveys,  72. 

Variation  of  the  compass:  10,  241;  daily  change, 241. 

Verifying  telescope  first  used  as  mine-transit  by  Hoskold,  44. 

Vernier :  invented,  16,  209  ;  on  vertical  arc,  one  or  two,  210. 

Vertical  circle:  advantage  of  a  full,  272 ;  full,  with  one  vernier,  75,  210,  219,  272. 

Viertel's,  Prof.,  first  use  of  the  eccentric  theodolite,  for  vertical  shaft  surveys,  21. 

Voigtel,  Nicholas:  first  treatise  on  mining  engineering,  7;  mining  astrolabe,  119; 

Setz-compass,  219. 
Von  Voith's  theodolite,  84. 

Von  Miller-Hauenfels's  rules  for  the  Gradbogen,  134  et  seq. 
Von  Oppel's  Eisenscheibe,  86. 

Wagoner's  (Luther)  cyclotomic  circles,  50,  120. 
Watt,  James,  discoverer  of  tacheometric  principle,  70. 

Weisbach's :  hanging-lamp,  303  ;  method  of  suspending  compass-box,  [24] ;  Setzlampe, 
305,  306. 


INDEX.  323 

Williams  (Butler)  suggested  (1842)  use  of  improved  theodolite  in  mine  surveys,  96. 
WITTSTOCK,  P.  AND  K. :  remarks  in  discussion  of  Mr.  Scott's  paper  on  the  evolution 

of  mine-surveying  instruments,  136. 
Wollaston  (W.  H.)  first  used  platinum  cross- wires  in  telescopes,  302. 

Yeiser's  (F.)  meridian-instrument,  177. 

YOUNG,  ALFRED  C. :  remarks  in  discussion  of  Mr.  Scott's  paper  on  the  evolution  of 
mine-surveying  instruments,  152. 

Young's  (W.  J.)  centesimal  graduation,  29 ;  "first  American  transit,"  25,  66,  67, 153 ; 
first  compound  "  long-center  "  transit,  153 ;  begins  in  1820  to  manufacture  sur- 
veying instruments,  152;  invention  of  the  transit,  25,  67,  153,  298;  shifting  tri- 
pod-head, 36,  153,  274,  291 ;  railway -transit,  298. 

Young  &  Son's  gradienter,  159 ;  modern  mine-transit,  161. 

Zollman's  Disk  (Scheibe),  167,  168 ;  classified  place,  289. 


ERRATA. 

Page  3,  line  2  from  bottom.  "  Minister  "  should  be  "  Miin- 
ster." 

Page  4,  line  5.     "  Beyern  "  should  be  "  Beyer." 
Page  4,  line  IT.     "  2364  "  should  be  «  2634." 
Page  5,  lines  3  and  4  from  bottom.      "  Diggs  "  should  be 
"  Digges  "  and  "  Leonhard  "  should  be  "  Leonard." 
Page  6,  line  1.     "  Theodolitus"  should  be  "  theodelitus." 
Page  6,  line  2  from  bottom.     "  The  same  year  "  should  be 
"  1579,"  and  "  Stratiaticus  "  should  be  "  Stratioticos." 

Page  7,  line  15.  "1590"  should  be  "1608."  The  tele- 
scope given  then  to  Prince  Maurice  was  made  by  Lippershey, 
not  Jansen. 

Page  7,  line  19.     "  1608  "  should  be  "  1609." 
Page  9,  line  1.     The  reference  here  made  is  to  Hohere  Mark- 
scheidekunst,  by  Prof.  Albert  von  Miller-Hauenfels,  Wien,  1868, 
pp.  286-291. 

Page  11,  line  8  from  bottom.  "  Strum  "  should  be  "  Sturm." 
See  his  Vier  kurze  Abhandlungen,  of  which  the  fourth  treats  of 
the  Markscheidekunst  als  ein  Anhang  dem  kurzen  Begriff  der  ge- 
sammten  Mathesis  beizufiigen,  Frankfurt  a.  d.  O.,  1710. 

Page  11,  line  4  from  bottom.  After  "  J.  G.  Studer,"  add: 
See  Ueber  Eisenscheiben.  Frdberger  gemeinnutzige  Nachrichten, 
No.  50,  1802.  Moll's  Annalen,  II.,  p.  387. 

Page  12,  line  2  from  bottom.      "  1537  "  should  be  "  1590." 

22 


324  ERRATA. 

Page  12,  line  2  from  bottom.     After  "  Leonhard  Zubler," 

add :    See  his  Fabrica  et    Usus  Instrumenti  Chorogr aphid,  Basel, 

1625. 

Page  13,  line  12  from  bottom.     After  "  Dr.  Lamont "  insert 

(1840). 

Page  16,  line  11.     "  Helvetius  "  should  be  "  Hevelius." 
Page    16,   line    6    from    bottom.      "  Guiliani "    should   be 

"  Giuliani." 

Page    19,  lines    16  and  17.     "Dolland"  should  be  "Dol- 

lond." 

Page  19,  line  4  from  bottom.     "  1669  "  should  be  "  1667." 
Page   20,  line    15    from    bottom.       "  Bourne "    should   be 

"  Bourns." 

Page  21,  at  bottom.  "Bohm"  should  be  "Bcehm." 

Page  28,  line  16.     "  1845  "  should  be  "  1836." 

Page  43,  line  4.     "  Gascoign  "  should  be  "  Gascoigne." 

Page  45,  line  11.    "British"  should  be  "Argentine  Mining 

and  Metallurgical." 

Page  61,  line  10  from  bottom.     "  Up  "  should  be  "  upon." 
Page  61,  line   5  from  bottom.     "  Steep  horizontal  angles  " 

should   be    "horizontal   angles   measured  with  the  telescope 

steeply  inclined." 

Page    62,   line    10    from    bottom.      "Kelner"    should    be 

«  Kellner." 

Page  272,  foot  note,  for  "  210  "  read  "  219." 


TL    oo/ol 


4  c  • 


